diff --git a/eden/mononoke/tests/integration/library.sh b/eden/mononoke/tests/integration/library.sh
index 4958fc7d21..77f441d99a 100644
--- a/eden/mononoke/tests/integration/library.sh
+++ b/eden/mononoke/tests/integration/library.sh
@@ -526,6 +526,8 @@ function setup_common_hg_configs {
   cat >> "$HGRCPATH" <<EOF
 [ui]
 ssh="$DUMMYSSH"
+[devel]
+segmented-changelog-rev-compat=True
 [extensions]
 remotefilelog=
 [remotefilelog]
diff --git a/eden/mononoke/tests/integration/test-edenapi-land-stack.t b/eden/mononoke/tests/integration/test-edenapi-land-stack.t
index 701eb32e0d..0bf210f08a 100644
--- a/eden/mononoke/tests/integration/test-edenapi-land-stack.t
+++ b/eden/mononoke/tests/integration/test-edenapi-land-stack.t
@@ -71,7 +71,7 @@ Test land stack
 
 Inspect results
   $ hgedenapi pull -q
-  $ hgedenapi log -G -T '{node} {desc}\n' -r "all()"
+  $ hgedenapi log -G -T '{node} {desc}\n' -r "sort(all(),topo)"
   o  cee85bb77dff9258b0b36fbe83501f3fd953fc4d E
   │
   o  c5ef64ddf563718659b4c9777f0110de43055135 D
@@ -80,14 +80,14 @@ Inspect results
   │
   │ o  a22ebc2f5947b439a77147f07f4f3fe43355bfa3 H
   ├─╯
+  o  181938a6b0e46aedfaf17b5866659716bf974efa G
+  │
+  o  33441538d4aad7db588e456862f21997f3bc7a04 F
+  │
   │ o  9bc730a19041f9ec7cb33c626e811aa233efb18c E
   │ │
-  o │  181938a6b0e46aedfaf17b5866659716bf974efa G
-  │ │
   │ o  f585351a92f85104bff7c284233c338b10eb1df7 D
   │ │
-  o │  33441538d4aad7db588e456862f21997f3bc7a04 F
-  │ │
   │ o  26805aba1e600a82e93661149f2313866a221a7b C
   ├─╯
   o  112478962961147124edd43549aedd1a335e44bf B
diff --git a/eden/mononoke/tests/integration/test-megarepo-fixup-history.t b/eden/mononoke/tests/integration/test-megarepo-fixup-history.t
index c65dd99adb..88a28d9435 100644
--- a/eden/mononoke/tests/integration/test-megarepo-fixup-history.t
+++ b/eden/mononoke/tests/integration/test-megarepo-fixup-history.t
@@ -106,24 +106,23 @@ Start mononoke server
   $ hg log -f fbcode/file_with_correct_history -T "{node} {desc}\n"
   835251f7cda8fd1adddf414ce67d58090897e93a master commit 1
 
-  $ hg debugchangelog --migrate fullsegments
-  $ hg log -G -T "{desc} [{phase};{node|short}] {remotenames}" -r 'sort(::.,-topo,topo.firstbranch=desc("master commit"))' | sed '$d'
+  $ hg log -G -T "{desc} [{phase};{node|short}] {remotenames}" -r 'sort(::.,topo)' | sed '$d'
   @    history fixup [public;dcacf3dd28f1] default/master
   ├─╮
-  │ o  [MEGAREPO DELETE] history fixup (1) [public;d3b2dfc1d7dc]
+  │ o  [MEGAREPO DELETE] history fixup (0) [public;94932f105be0]
   │ │
-  │ o  [MEGAREPO DELETE] history fixup (0) [public;c2a5523610c4]
+  │ o  commit commit 3 [incorrect history] [public;c3f812992511]
   │ │
-  │ o  small repo commit 3 [public;ea8595b036ed]
+  │ o  commit commit 2 [incorrect history] [public;4f27e05b6e2a]
   │ │
-  │ o  small repo commit 2 [corrected history] [public;6c017a8ba0a6]
-  │ │
-  │ o  small repo commit 1 [public;11fbaaa53e1b]
+  │ o  master commit 1 [public;835251f7cda8]
   │
-  o  [MEGAREPO DELETE] history fixup (0) [public;94932f105be0]
+  o  [MEGAREPO DELETE] history fixup (1) [public;d3b2dfc1d7dc]
   │
-  o  commit commit 3 [incorrect history] [public;c3f812992511]
+  o  [MEGAREPO DELETE] history fixup (0) [public;c2a5523610c4]
   │
-  o  commit commit 2 [incorrect history] [public;4f27e05b6e2a]
+  o  small repo commit 3 [public;ea8595b036ed]
   │
-  o  master commit 1 [public;835251f7cda8]
+  o  small repo commit 2 [corrected history] [public;6c017a8ba0a6]
+  │
+  o  small repo commit 1 [public;11fbaaa53e1b]
diff --git a/eden/mononoke/tests/integration/test-megarepo-tool-sync-diamond-merge.t b/eden/mononoke/tests/integration/test-megarepo-tool-sync-diamond-merge.t
index 97568f7586..8881cad542 100644
--- a/eden/mononoke/tests/integration/test-megarepo-tool-sync-diamond-merge.t
+++ b/eden/mononoke/tests/integration/test-megarepo-tool-sync-diamond-merge.t
@@ -122,14 +122,14 @@ Create a branch merge in a small repo
   > EOF
   $ hg rebase -s $A -d with_merge_master -q
 
-  $ hg log -G -T '{node|short}'
+  $ hg log -r 'sort(all(),topo)' -G -T '{node|short}'
   o    62dba675d1b3
   ├─╮
   │ o  be5140c7bfcc
   │ │
-  o │  23aa3f5a6de2
-  │ │
   │ o  7a7632995e68
+  │ │
+  o │  23aa3f5a6de2
   ├─╯
   o  68360e2c98f0
   │
diff --git a/eden/mononoke/tests/integration/test-server-sqlblob.t b/eden/mononoke/tests/integration/test-server-sqlblob.t
index e410a7ec67..e71e4dc332 100644
--- a/eden/mononoke/tests/integration/test-server-sqlblob.t
+++ b/eden/mononoke/tests/integration/test-server-sqlblob.t
@@ -50,6 +50,7 @@ Init treemanifest and remotefilelog
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     a
    (re)
+  $ hg bookmark -r . master_bookmark
   $ cd $TESTTMP
 
 setup repo2
@@ -116,7 +117,7 @@ setup repo2
 
 setup master bookmarks
 
-  $ hg bookmark master_bookmark -r e635b24c95f7
+  $ hg bookmark master_bookmark -fr e635b24c95f7
   $ hg bookmark master_bookmark2 -r 9f8e7242d9fa
 
 blobimport
diff --git a/eden/mononoke/tests/integration/test-streaming-clone-tag.t b/eden/mononoke/tests/integration/test-streaming-clone-tag.t
index 79a41b3d3d..0cd311b783 100644
--- a/eden/mononoke/tests/integration/test-streaming-clone-tag.t
+++ b/eden/mononoke/tests/integration/test-streaming-clone-tag.t
@@ -6,6 +6,7 @@
 #require slow
 
   $ . "${TEST_FIXTURES}/library.sh"
+  $ setconfig format.use-segmented-changelog=false
 
 setup configuration
   $ default_setup_blobimport "blob_files"
diff --git a/eden/mononoke/tests/integration/test-streaming-clone.t b/eden/mononoke/tests/integration/test-streaming-clone.t
index 0d00b0a08e..3943440ad5 100644
--- a/eden/mononoke/tests/integration/test-streaming-clone.t
+++ b/eden/mononoke/tests/integration/test-streaming-clone.t
@@ -6,6 +6,7 @@
 #require slow
 
   $ . "${TEST_FIXTURES}/library.sh"
+  $ setconfig format.use-segmented-changelog=false
 
 setup configuration
   $ default_setup_blobimport "blob_files"
diff --git a/eden/scm/edenscm/changelog2.py b/eden/scm/edenscm/changelog2.py
index 3ff5402306..ba1d9cf8a7 100644
--- a/eden/scm/edenscm/changelog2.py
+++ b/eden/scm/edenscm/changelog2.py
@@ -28,7 +28,7 @@ from . import (
 )
 from .changelog import changelogrevision, gitcommittext, hgcommittext, readfiles
 from .i18n import _
-from .node import hex, nullid, nullrev, wdirid, wdirrev
+from .node import bin, hex, nullid, nullrev, wdirid, wdirrev
 
 
 SEGMENTS_DIR = "segments/v1"
@@ -419,6 +419,8 @@ class changelog(object):
             parents = [p for p in (p1, p2) if p != nullid]
             basetext = textmap.get(deltabase) or self.revision(deltabase)
             rawtext = bytes(mdiff.patch(basetext, delta))
+            if b"stepparents:" in rawtext:
+                parents += parse_stepparents(changelogrevision(rawtext).extra)
             textmap[node] = rawtext
             commits.append((node, parents, rawtext))
             # Attempt to make memory usage bound for large pulls.
@@ -692,6 +694,32 @@ class nodemap(object):
         pass
 
 
+# Old storage (revlog) and protocols (bundle2 - aka. addgroup()) use
+# "stepparents" extras to store >2 parents. This needs to be converted
+# back to real parents for newer backends.
+#
+# "stepparents" contains hex nodes joined by ",".
+#
+#                   | >2 parents  | >2 parents via |
+#                   | via parents | commit extra   |
+# --------------------------------------------------
+# storage: dag      | yes         | no             |
+# storage: revlog   | no [1]      | yes            |
+# protocol: bundle2 | no          | yes            |
+# protocol: edenapi | yes         | ignore         |
+#
+# [1]: support >2 parents in memory, but discard on flush
+#
+# See also D30686450.
+def parse_stepparents(extras):
+    """parse extra parent nodes from commit extras -> [node]"""
+    if extras:
+        stepparents = extras.get("stepparents")
+        if stepparents:
+            return [bin(h) for h in stepparents.split(",")]
+    return []
+
+
 def migrateto(repo, name):
     """Migrate from the current format to the destination format `name`."""
     if backendname(repo) == name:
diff --git a/eden/scm/edenscm/configitems.py b/eden/scm/edenscm/configitems.py
index 197565bef5..b7ee15624f 100644
--- a/eden/scm/edenscm/configitems.py
+++ b/eden/scm/edenscm/configitems.py
@@ -325,7 +325,8 @@ coreconfigitem("format", "dirstate", default=2)
 coreconfigitem("format", "manifestcachesize", default=None)
 coreconfigitem("format", "maxchainlen", default=None)
 coreconfigitem("format", "obsstore-version", default=None)
-coreconfigitem("format", "use-segmented-changelog", default=False)
+coreconfigitem("format", "usegeneraldelta", default=True)
+coreconfigitem("format", "use-segmented-changelog", default=util.istest())
 coreconfigitem("fsmonitor", "warn_when_unused", default=True)
 coreconfigitem("fsmonitor", "warn_update_file_count", default=50000)
 coreconfigitem("git", "submodules", default=True)
diff --git a/eden/scm/edenscm/ext/extlib/watchmanclient/__init__.py b/eden/scm/edenscm/ext/extlib/watchmanclient/__init__.py
index 6345099400..46e99529bc 100644
--- a/eden/scm/edenscm/ext/extlib/watchmanclient/__init__.py
+++ b/eden/scm/edenscm/ext/extlib/watchmanclient/__init__.py
@@ -333,9 +333,16 @@ class client(object):
 
 # Estimate the distance between two nodes
 def calcdistance(repo, oldnode, newnode):
-    anc = repo.changelog.ancestor(oldnode, newnode)
-    ancrev = repo[anc].rev()
-    distance = abs(repo[oldnode].rev() - ancrev) + abs(repo[newnode].rev() - ancrev)
+    cl = repo.changelog
+    if cl.algorithmbackend == "segments":
+        only = cl.dag.only
+        distance1 = len(only([oldnode], [newnode]))
+        distance2 = len(only([newnode], [oldnode]))
+        distance = distance1 + distance2
+    else:
+        anc = repo.changelog.ancestor(oldnode, newnode)
+        ancrev = repo[anc].rev()
+        distance = abs(repo[oldnode].rev() - ancrev) + abs(repo[newnode].rev() - ancrev)
     return distance
 
 
diff --git a/eden/scm/lib/repo/src/init.rs b/eden/scm/lib/repo/src/init.rs
index c60d1826e4..849bc96deb 100644
--- a/eden/scm/lib/repo/src/init.rs
+++ b/eden/scm/lib/repo/src/init.rs
@@ -140,7 +140,7 @@ fn write_store_requirements(path: &Path, config: &ConfigSet) -> Result<(), InitE
     create_dir(store_path)?;
     let mut requirements = HashSet::from(["visibleheads"]);
     if config
-        .get_or("format", "use-segmented-changelog", || false)
+        .get_or("format", "use-segmented-changelog", is_test)
         .unwrap_or(false)
     {
         requirements.insert("invalidatelinkrev");
@@ -157,6 +157,10 @@ fn write_store_requirements(path: &Path, config: &ConfigSet) -> Result<(), InitE
     write_requirements_file(store_path, requirements)
 }
 
+fn is_test() -> bool {
+    std::env::var_os("TESTTMP").is_some()
+}
+
 #[cfg(test)]
 mod tests {
     use configparser::config::Options;
diff --git a/eden/scm/lib/revlogindex/src/revlogindex.rs b/eden/scm/lib/revlogindex/src/revlogindex.rs
index df666f44d9..a18a6f135b 100644
--- a/eden/scm/lib/revlogindex/src/revlogindex.rs
+++ b/eden/scm/lib/revlogindex/src/revlogindex.rs
@@ -853,7 +853,7 @@ impl RevlogIndex {
 
             let mut parent_revs: [i32; 2] = [-1, -1];
             let parents = &parent_map[node.as_ref()];
-            for (p_id, p_node) in parents.iter().enumerate() {
+            for (p_id, p_node) in parents.iter().take(2).enumerate() {
                 parent_revs[p_id] = get_rev(&existing_nodes, p_node)? as i32;
             }
 
diff --git a/eden/scm/tests/edit-feature-header.py b/eden/scm/tests/edit-feature-header.py
index aa1525b3cb..ff5063d067 100755
--- a/eden/scm/tests/edit-feature-header.py
+++ b/eden/scm/tests/edit-feature-header.py
@@ -42,17 +42,10 @@ FEATURES = [
     Feature("no-chg", "#chg-incompatible\n"),
     Feature("debugruntest", "#debugruntest-compatible\n"),
     Feature("no-treemanifest", "  $ disable treemanifest\n"),
-    Feature(
-        "no-narrowheads",
-        "  $ setconfig experimental.narrow-heads=false\n",
-    ),
-    Feature(
-        "no-segmented-changelog",
-        "  $ setconfig format.use-segmented-changelog=true\n",
-    ),
     Feature("no-ignore-revnum", "  $ setconfig ui.ignorerevnum=false\n"),
     Feature("py2", "#require py2\n"),
     Feature("no-inprocess-hg", "#inprocess-hg-incompatible\n"),
+    Feature("rev-compat", "  $ setconfig devel.segmented-changelog-rev-compat=true\n"),
 ]
 
 
diff --git a/eden/scm/tests/features.py b/eden/scm/tests/features.py
index 9fc8b50770..69c297be39 100644
--- a/eden/scm/tests/features.py
+++ b/eden/scm/tests/features.py
@@ -11,578 +11,6 @@ But for now it's easier than changing configs at the top of individual
 tests.
 """
 
-segmentedchangelogcompatiblelist = """
-    test-abort-checkin.t
-    test-absorb-edit-lines.t
-    test-absorb-phase.t
-    test-absorb-remotefilelog-segments.t
-    test-absorb-strip.t
-    test-add.t
-    test-adding-invalid-utf8.t
-    test-addremove-similar.t
-    test-alias-circular.t
-    test-alias.t
-    test-alias2.t
-    test-amend-next.t
-    test-amend-previous.t
-    test-amend-rebase-inmemory.t
-    test-amend-restack-auto.t
-    test-amend-restack-divergence.t
-    test-amend-restack-multidest.t
-    test-amend-restack-obsolete.t
-    test-amend-split.t
-    test-amend-template.t
-    test-amend-to.t
-    test-amend-userestack.t
-    test-amend.t
-    test-annotate.py
-    test-arbitraryfilectx.t
-    test-archive-symlinks.t
-    test-argspans.py
-    test-atomictempfile.py
-    test-auth-match.t
-    test-autofix.t
-    test-bad-extension.t
-    test-bad-pull.t
-    test-basic.t
-    test-batching.py
-    test-bdiff.py
-    test-bindag.t
-    test-bisect3.t
-    test-bookmarks-current.t
-    test-bookmarks-loading-order.t
-    test-bookmarks-merge.t
-    test-bookmarks-rebase.t
-    test-bookmarks-strip.t
-    test-bookmarkstore.py
-    test-casecollision.t
-    test-changelog-exec.t
-    test-check-clang-format.t
-    test-check-code.t
-    test-check-execute.t
-    test-check-fix-code.t
-    test-check-help.t
-    test-check-interfaces.py
-    test-check-win32-signature.py
-    test-checkoutidentifier-commitinfo.t
-    test-checkoutidentifier-dirstateinfo.t
-    test-clienttelemetry.t
-    test-command-template2.t
-    test-commit-amend.t
-    test-commit-interactive-curses.t
-    test-commit-reuse.t
-    test-commit-revive.t
-    test-commit-size-limits.t
-    test-commit-unresolved.t
-    test-commitcloud-background-logging-perms.t
-    test-commitcloud-backup-compression.t
-    test-commitcloud-backup-logging.t
-    test-commitcloud-backup-remotenames.t
-    test-commitcloud-backup-share.t
-    test-commitcloud-checkoutlocations-update.t
-    test-commitcloud-list-workspaces.t
-    test-commitcloud-smartlog-version.t
-    test-commitcloud-smartlog.t
-    test-commitcloud-sync-rb-enabling.t
-    test-commitcloud-sync-workspacenames.t
-    test-committer.t
-    test-completion.t
-    test-config-configfile.t
-    test-config.t
-    test-configparser.py
-    test-conflict.t
-    test-contrib-check-code.t
-    test-copytrace-manual.t
-    test-crdump-commitcloud.t
-    test-ctrl-c.t
-    test-custom-filters.t
-    test-debugbundle-rebase.t
-    test-debugbundle.t
-    test-debugcauserusterror.t
-    test-debugcheckcasecollisions-treemanifest.t
-    test-debugcommands.t
-    test-debugdifftree.t
-    test-debugdirs.py
-    test-debugdynamicconfig.t
-    test-debugexistingcasecollisions.t
-    test-debugextensions.t
-    test-debugignore.t
-    test-debugmetalog.t
-    test-debugrebuilddirstate-corrupt.t
-    test-debugshell-args.t
-    test-debugsmallcommitmetadata.t
-    test-debugthrowrustexception.t
-    test-demandimport.py
-    test-deprecate.t
-    test-devel-warnings.t
-    test-diff-antipatience.t
-    test-diff-binary.t
-    test-diff-color.t
-    test-diff-copy-depth.t
-    test-diff-hashbinary.t
-    test-diff-ignore-whitespace.t
-    test-diff-indent-heuristic.t
-    test-diff-subdir.t
-    test-diff-unified.t
-    test-diff-upgrade.t
-    test-diffstat.t
-    test-dirstate-backup.t
-    test-dirstate-completion.t
-    test-dirstate-nonnormalset.t
-    test-dirstate-rebuild.t
-    test-dirstate-symlink.t
-    test-dirstate.t
-    test-disable-bad-features.t
-    test-disablesymlinks.t
-    test-dispatch-debug-prefix.t
-    test-dispatch.t
-    test-doctest.py
-    test-dott-quote.t
-    test-dott-translate.py
-    test-duplicateoptions.py
-    test-dynamicconfig-unicode.t
-    test-edit-tmp.t
-    test-editor-filename.t
-    test-empty-dir.t
-    test-empty-file.t
-    test-encode.t
-    test-encoding-align.t
-    test-encoding-func.py
-    test-encoding-textwrap.t
-    test-eolfilename.t
-    test-execute-bit.t
-    test-exitcodemask.t
-    test-extension-ext-prefix.t
-    test-extension-inline.t
-    test-extensions-afterloaded.t
-    test-extensions-default.t
-    test-extensions-wrapfunction.py
-    test-fb-ext-absorb-filefixupstate.py
-    test-fb-ext-arcconfig.t
-    test-fb-ext-catnotate.t
-    test-fb-ext-checkmessagehook.t
-    test-fb-ext-copytrace-amend.t
-    test-fb-ext-copytrace-mergedriver.t
-    test-fb-ext-debugcommitmessage.t
-    test-fb-ext-diff-since-last-submit.t
-    test-fb-ext-errorredirect.t
-    test-fb-ext-extorder.t
-    test-fb-ext-extutil.py
-    test-fb-ext-fastannotate-revmap.py
-    test-fb-ext-fbhistedit-exec-obsolete.t
-    test-fb-ext-fbhistedit-exec.t
-    test-fb-ext-fbhistedit-graft.t
-    test-fb-ext-fbhistedit-json.t
-    test-fb-ext-fbhistedit-show-plan.t
-    test-fb-ext-fbhistedit-stop-obsolete.t
-    test-fb-ext-fbhistedit-stop.t
-    test-fb-ext-generic-bisect.py
-    test-fb-ext-githelp.t
-    test-fb-ext-grpcheck.t
-    test-fb-ext-morestatus.t
-    test-fb-ext-myparent.t
-    test-fb-ext-ownercheck-t.py
-    test-fb-ext-patchrmdir.py
-    test-fb-ext-phabdiff.t
-    test-fb-ext-phabstatus.t
-    test-fb-ext-rage.t
-    test-fb-ext-remotefilelog-bundleloop.t
-    test-fb-ext-remotefilelog-commit-repack.t
-    test-fb-ext-remotefilelog-datapack.py
-    test-fb-ext-remotefilelog-histpack.py
-    test-fb-ext-remotefilelog-localdatarepack-full.t
-    test-fb-ext-remotefilelog-rust-lfs.t
-    test-fb-ext-remotefilelog-ruststores-lfs-bundle.t
-    test-fb-ext-remotefilelog-ruststores-lfs-duplicated.t
-    test-fb-ext-sampling.t
-    test-fb-ext-scm-prompt-compat.t
-    test-fb-ext-scm-prompt-git.t
-    test-fb-ext-scm-prompt-hg.t
-    test-fb-ext-sigtrace.t
-    test-fb-ext-simplecache.t
-    test-fb-ext-smartlog-smallcommitmetadata.t
-    test-fb-ext-smartlog.t
-    test-fb-ext-sshaskpass.py
-    test-fb-ext-syncstatus.t
-    test-fb-ext-template-stat.t
-    test-fb-ext-treemanifest-bad-tree.t
-    test-fb-ext-treemanifest-convertflat.t
-    test-fb-ext-treemanifest-sendtrees.t
-    test-fb-ext-treemanifest-sparse-prefetch.t
-    test-fb-ext-treemanifest-sparse.t
-    test-fb-ext-tweakdefaults-bookmarks.t
-    test-fb-ext-tweakdefaults-grep.t
-    test-fb-ext-tweakdefaults-opawarecommands.t
-    test-fb-ext-tweakdefaults-ordering.t
-    test-fb-ext-tweakdefaults-revsets.t
-    test-filecache.py
-    test-filelog.py
-    test-fileset-generated.t
-    test-getbundle.t
-    test-git.t
-    test-gitignore.t
-    test-globalrevs-svnrev.t
-    test-help.t
-    test-hg-parseurl.py
-    test-ext-logginghelper.t
-    test-hghave.t
-    test-hgrc.t
-    test-hint.t
-    test-histedit-bookmark-motion.t
-    test-histedit-drop.t
-    test-histedit-fold-non-commute.t
-    test-histedit-fold.t
-    test-histedit-non-commute-abort.t
-    test-histedit-non-commute.t
-    test-histedit-templates.t
-    test-hybridencode.py
-    test-import-context.t
-    test-import-eol.t
-    test-import-git.t
-    test-include-fail.t
-    test-infinitepush-push-to-other.t
-    test-install.t
-    test-issue1089.t
-    test-issue1877.t
-    test-issue2137.t
-    test-issue4074.t
-    test-known.t
-    test-lfs-journal.t
-    test-lfs-localstore.t
-    test-lfs-pointer.py
-    test-linelog-edits.py
-    test-linerange.py
-    test-lock.py
-    test-log-dir.t
-    test-log-exthook.t
-    test-log-simplify-grandparents.t
-    test-lrucachedict.py
-    test-manifest-insert-before-remove.py
-    test-manifest.py
-    test-match.py
-    test-merge-changedelete.t
-    test-merge-conflict-count.t
-    test-merge-force.t
-    test-merge-halt.t
-    test-merge-internal-tools-pattern.t
-    test-merge-issue5091.t
-    test-merge-local.t
-    test-merge-relative-paths.t
-    test-merge-update-noconflict.t
-    test-merge2.t
-    test-mergedriver2.t
-    test-metalog-migration-t.py
-    test-minirst.py
-    test-mkdir-broken-symlink.t
-    test-mmap-unlink.t
-    test-mutation-fromobsmarkers.t
-    test-mutation-loops.t
-    test-mutation-phases.t
-    test-namespaces.t
-    test-narrow-heads-migration.t
-    test-nested-repo.t
-    test-origbackup-conflict.t
-    test-patch-offset.t
-    test-pathconflicts-update.t
-    test-pathencode.py
-    test-paths.t
-    test-patterns.t
-    test-perftrace.t
-    test-perftweaks.t
-    test-profile.t
-    test-progress-classicrenderer.t
-    test-progress-fancyrenderer.t
-    test-progress-rust.t
-    test-progressfile.t
-    test-purge.t
-    test-pushrebase-obsolete.t
-    test-rebase-base-flag.t
-    test-rebase-copy-relations.t
-    test-rebase-inmemory-conflicts.t
-    test-rebase-inmemory-mergedriver-exception.t
-    test-rebase-missing-cwd.t
-    test-rebase-partial.t
-    test-rebase-templates.t
-    test-rebase-transaction.t
-    test-rebuildstate.t
-    test-record.t
-    test-remotenames-paths.t
-    test-remove.t
-    test-repo-leak.t
-    test-requires.t
-    test-restack-old-stack.t
-    test-revert-flags.t
-    test-revert-interactive.t
-    test-revert-status.t
-    test-revlog-packentry.t
-    test-revlog-raw.py
-    test-revset-dirstate-parents.t
-    test-root.t
-    test-run-tests.py
-    test-rust-rmcwd.t
-    test-rust-subcommands.t
-    test-rustthreading.py
-    test-seq.t
-    test-serve.t
-    test-share-requirements.t
-    test-share-unshare.t
-    test-show.t
-    test-simplekeyvaluefile.py
-    test-simplemerge.py
-    test-smartlog-collapse-obsolete.t
-    test-sortdictfilter.t
-    test-sparse-casecollision.t
-    test-sparse-clear.t
-    test-sparse-diff.t
-    test-sparse-extensions.t
-    test-sparse-fetch.t
-    test-sparse-ignore.t
-    test-sparse-import.t
-    test-sparse-issues.t
-    test-sparse-merges.t
-    test-sparse-notsparse.t
-    test-sparse-profiles.t
-    test-sparse-rebase.t
-    test-sparse-unsafe-sparse-profile.t
-    test-sparse-warn.t
-    test-sshserver.py
-    test-status-color.t
-    test-status-inprocess.py
-    test-status-mlog.t
-    test-status-terse.t
-    test-subcommands.t
-    test-template-filestat.t
-    test-tools.t
-    test-treemanifest-amend.t
-    test-treemanifest-diff.t
-    test-treestate-needcheck.t
-    test-treestate-repack.t
-    test-treestate-upgrade-t.py
-    test-treestate.py
-    test-ui-color.py
-    test-ui-config.py
-    test-ui-verbosity.py
-    test-uncommit.t
-    test-undo-narrow-heads.t
-    test-unicode-inputs.t
-    test-unified-test.t
-    test-update-inactive.t
-    test-update-issue1456.t
-    test-update-merge-state.t
-    test-update-reverse.t
-    test-update-symlink-to-plain.t
-    test-url.py
-    test-username-newline.t
-    test-visibility-reset.t
-    test-walk.t
-    test-walkrepo.py
-    test-wireproto.py
-    test-wireproto.t
-    test-worker.t
-    test-xdg.t
-    test-zstdelta.py
-
-    test-addremove.t
-    test-amend-nextrebase.t
-    test-audit-path.t
-    test-backout.t
-    test-bisect2.t
-    test-blackbox.t
-    test-bundle2-multiple-changegroups.t
-    test-bundle-type.t
-    test-commit-amend-reuse-rawfctx.t
-    test-commitcloud-backup-all.t
-    test-commitcloud-backup-lfs.t
-    test-commitcloud-backup-remotenames-public.t
-    test-commitcloud-backup-restore-obsolete.t
-    test-commitcloud-backup-restore.t
-    test-commitcloud-backup-rev.t
-    test-commitcloud-backup-status.t
-    test-commitcloud-lazypull-phab.t
-    test-commitcloud-lazypull.t
-    test-commitcloud-rename-workspace.t
-    test-commitcloud-sync-migration.t
-    test-commitcloud-sync-race.t
-    test-commitcloud-sync-rb-deletion.t
-    test-commitcloud-sync-rb-enabling2.t
-    test-commitcloud-sync.t
-    test-commitcloud-update.t
-    test-commit-interactive.t
-    test-commit.t
-    test-copy-move-merge.t
-    test-copytrace-heuristics.t
-    test-debugsendunbundle.t
-    test-double-merge.t
-    test-encoding.t
-    test-eol-add.t
-    test-eol-patch.t
-    test-eol.t
-    test-fb-ext-copytrace.t
-    test-fb-ext-crdump.t
-    test-fb-ext-debugdetectissues.t
-    test-fb-ext-dirsync-amend.t
-    test-fb-ext-dirsync.t
-    test-fb-ext-git-getmeta.t
-    test-fb-ext-merge-conflictinfo.t
-    test-fb-ext-mergedriver.t
-    test-fb-ext-pull-createmarkers.t
-    test-fb-ext-pushrebase-protection.t
-    test-fb-ext-pushvars-remotenames.t
-    test-fb-ext-remotefilelog-archive.t
-    test-fb-ext-remotefilelog-bad-configs.t
-    test-fb-ext-remotefilelog-bundle2-legacy.t
-    test-fb-ext-remotefilelog-bundle2.t
-    test-fb-ext-remotefilelog-bundles.t
-    test-fb-ext-remotefilelog-getpackv2.t
-    test-fb-ext-remotefilelog-local.t
-    test-fb-ext-remotefilelog-pull-noshallow.t
-    test-fb-ext-remotefilelog-push-pull-query-string.t
-    test-fb-ext-remotefilelog-ruststores-repack.t
-    test-fb-ext-remotefilelog-ruststores-rotatelog-size.t
-    test-fb-ext-remotefilelog-treemanifest-corrupt.t
-    test-fb-ext-remotefilelog-worker.t
-    test-fb-ext-reset-remotenames.t
-    test-fb-ext-treemanifest-blame.t
-    test-fb-ext-treemanifest-comparetrees.t
-    test-fb-ext-treemanifest-disabled.t
-    test-fb-ext-treemanifest-infinitepush.t
-    test-fb-ext-treemanifest-peertopeer.t
-    test-fb-ext-treemanifest-pushrebase.t
-    test-fb-ext-treemanifest-pushrebase-treeonly.t
-    test-fb-ext-treemanifest-remotenames-out-of-sync.t
-    test-fb-ext-treemanifest-treeonly-copyamend.t
-    test-fb-ext-treemanifest-treeonly-fetching.t
-    test-fb-ext-tweakdefaults-remotenames.t
-    test-gitlookup-infinitepush.t
-    test-globalopts.t
-    test-ext-stablerev.t
-    test-histedit-arguments.t
-    test-histedit-base.t
-    test-histedit-commute.t
-    test-histedit-mutation.t
-    test-histedit-no-change.t
-    test-histedit-outgoing.t
-    test-important-remote-names-t.py
-    test-import-bypass.t
-    test-infinitepush-bundlestore.t
-    test-infinitepush-delscratchbookmarks.t
-    test-infinitepush-publicscratchbookmarks.t
-    test-infinitepush-remotefilelog.t
-    test-infinitepush-remotenames.t
-    test-infinitepush-scratchbookmark-commands.t
-    test-init.t
-    test-issue1502.t
-    test-issue522.t
-    test-issue586.t
-    test-issue672.t
-    test-journal-share.t
-    test-journal.t
-    test-lfs-checksum.t
-    test-lock-badness.t
-    test-log-wireproto-requests-getpack.t
-    test-log-wireproto-requests.t
-    test-merge1.t
-    test-merge6.t
-    test-merge8-t.py
-    test-merge-criss-cross.t
-    test-merge-remove.t
-    test-merge-symlinks.t
-    test-merge-types.t
-    test-mutation-infinitepush.t
-    test-mutation-pushrebase.t
-    test-mutation.t
-    test-narrow-heads.t
-    test-pathconflicts-basic.t
-    test-pathconflicts-merge.t
-    test-pending.t
-    test-perftweaks-remotenames.t
-    test-pushvars.t
-    test-rebase-bookmarks.t
-    test-rebase-collapse.t
-    test-rebase-conflicts.t
-    test-rebase-dest.t
-    test-rebase-detach.t
-    test-rebase-flags.t
-    test-rebase-inmemory-mergedriver.t
-    test-rebase-inmemory-nochanges.t
-    test-rebase-inmemory-noconflict.t
-    test-rebase-inmemory.t
-    test-rebase-interruptions.t
-    test-rebase-newancestor.t
-    test-rebase-removed.t
-    test-rebase-rename.t
-    test-remotefilelog-undesired-file-logging.t
-    test-remotenames-basic.t
-    test-remotenames-convert-t.py
-    test-remotenames-fastheaddiscovery-hidden-commits.t
-    test-remotenames-journal.t
-    test-remotenames-namespaces.t
-    test-remotenames-on-and-off-t.py
-    test-remotenames-pull-rebase.t
-    test-remotenames-push.t
-    test-remotenames-pushto-pathandname.t
-    test-remotenames-pushto.t
-    test-remotenames-selective-pull-accessed-bookmarks.t
-    test-remotenames-selective-pull.t
-    test-remotenames-strip.t
-    test-remotenames-transition.t
-    test-rename-after-merge.t
-    test-rename-dir-merge.t
-    test-rename-merge1.t
-    test-rename.t
-    test-resolve.t
-    test-revset-outgoing.t
-    test-share.t
-    test-sparse-clone.t
-    test-sparse.t
-    test-symlink-os-yes-fs-no.py
-    test-symlink-placeholder.t
-    test-symlinks.t
-    test-unrelated-pull.t
-    test-update-dest.t
-    test-update-names.t
-    test-up-local-change.t
-    test-url-rev.t
-    test-visibility-bundle.t
-    test-visibility-cloudsync.t
-    test-visibility.t
-
-    test-rebase-abort.t
-    test-rebase-brute-force.t
-    test-rebase-check-restore.t
-    test-rebase-emptycommit.t
-
-    test-clone-resume.t
-    test-clone-uncompressed.t
-
-    test-commitcloud-sync-bookmarks.t
-    test-commitcloud-sync-omission.t
-    test-commitcloud-sync-remote-bookmarks.t
-
-    test-debugrebuildchangelog.t
-    test-doctor.t
-
-    test-fb-ext-pull-createmarkers-hide-later.t
-
-    test-fb-ext-remotefilelog-blame.t
-    test-fb-ext-remotefilelog-push-pull.t
-    test-fb-ext-remotefilelog-sparse.t
-    test-fb-ext-remotefilelog-treemanifest-lfs.t
-
-    test-fb-ext-treemanifest-autoconvert.t
-    test-fb-ext-treemanifest-prefetch.t
-    test-fb-ext-treemanifest-pullpublic.t
-    test-fb-ext-treemanifest-treeonly.t
-    test-fb-ext-treemanifest.t
-
-    test-pushrebase-withmerges.t
-    test-rebase-mutation.t
-    test-rebase-scenario-global.t
-
-    test-context.py
-    test-rustmanifest.t
-"""
-
 ignorerevnumincompatiblelist = """
     test-alias.t
     test-amend-hide.t
@@ -725,10 +153,6 @@ def setup(testname, hgrcpath):
     # Disable mutation.record to maintain commit hashes.
     with open(hgrcpath, "a") as f:
         f.write("\n[mutation]\nrecord=False\n")
-    # Enable segmented changelog if compatible.
-    if testname in segmentedchangelogcompatiblelist:
-        with open(hgrcpath, "a") as f:
-            f.write("\n[format]\nuse-segmented-changelog=True\n")
     # Support legacy revnum for incompatible tests.
     if testname in ignorerevnumincompatiblelist:
         with open(hgrcpath, "a") as f:
diff --git a/eden/scm/tests/test-absorb-remotefilelog-segments.t b/eden/scm/tests/test-absorb-remotefilelog-segments.t
index 64c9c11174..2f311d0031 100644
--- a/eden/scm/tests/test-absorb-remotefilelog-segments.t
+++ b/eden/scm/tests/test-absorb-remotefilelog-segments.t
@@ -1,5 +1,4 @@
 #debugruntest-compatible
-  $ setconfig format.use-segmented-changelog=1
   $ enable absorb remotefilelog
 
 Create repo
diff --git a/eden/scm/tests/test-basic.t b/eden/scm/tests/test-basic.t
index 17bf2bd1d9..4955f7674e 100644
--- a/eden/scm/tests/test-basic.t
+++ b/eden/scm/tests/test-basic.t
@@ -5,8 +5,6 @@
 
 Create a repository:
 
-  $ setconfig format.use-segmented-changelog=1
-
   $ hg config
   commands.status.relative=true
   config.use-rust=true
@@ -16,7 +14,6 @@ Create a repository:
   experimental.metalog=true
   extensions.fsmonitor= (fsmonitor !)
   extensions.treemanifest=!
-  format.use-segmented-changelog=1
   fsmonitor.detectrace=1 (fsmonitor !)
   hint.ack-match-full-traversal=true
   mutation.record=False
diff --git a/eden/scm/tests/test-fb-ext-smartlog.t b/eden/scm/tests/test-fb-ext-smartlog.t
index 22ca31ee1a..cd5c6a6103 100644
--- a/eden/scm/tests/test-fb-ext-smartlog.t
+++ b/eden/scm/tests/test-fb-ext-smartlog.t
@@ -6,8 +6,6 @@
   $ disable treemanifest
   $ enable smartlog
   $ readconfig <<EOF
-  > [format]
-  > use-segmented-changelog=1
   > [experimental]
   > graphstyle.grandparent=|
   > graphstyle.missing=|
diff --git a/eden/scm/tests/test-fsmonitor-filemerge.t b/eden/scm/tests/test-fsmonitor-filemerge.t
index 505250e82a..1a1ebf30a9 100644
--- a/eden/scm/tests/test-fsmonitor-filemerge.t
+++ b/eden/scm/tests/test-fsmonitor-filemerge.t
@@ -24,9 +24,9 @@
   [1]
 
   $ hg blackbox --no-timestamp --no-sid --pattern '{"watchman":"_"}' | egrep '(watchman.*state.*)'
-  [watchman] command ["state-enter",{"metadata":{"distance":3,"merge":false,"partial":false,"rev":"0000000000000000000000000000000000000000","status":"ok"},"name":"hg.update"}] finished in 0 ms
-  [watchman] command ["state-leave",{"metadata":{"distance":3,"merge":false,"partial":false,"rev":"2e2f27616b65209eecd4710c454df0f678f271d9","status":"ok"},"name":"hg.update"}] finished in 0 ms
-  [watchman] command ["state-enter",{"metadata":{"distance":3,"merge":true,"partial":false,"rev":"2e2f27616b65209eecd4710c454df0f678f271d9","status":"ok"},"name":"hg.update"}] finished in 0 ms
+  [watchman] command ["state-enter",{"metadata":{"distance":2,"merge":false,"partial":false,"rev":"0000000000000000000000000000000000000000","status":"ok"},"name":"hg.update"}] finished in 0 ms
+  [watchman] command ["state-leave",{"metadata":{"distance":2,"merge":false,"partial":false,"rev":"2e2f27616b65209eecd4710c454df0f678f271d9","status":"ok"},"name":"hg.update"}] finished in 0 ms
+  [watchman] command ["state-enter",{"metadata":{"distance":2,"merge":true,"partial":false,"rev":"2e2f27616b65209eecd4710c454df0f678f271d9","status":"ok"},"name":"hg.update"}] finished in 0 ms
   [watchman] command ["state-enter",{"metadata":{"path":"2"},"name":"hg.filemerge"}] finished in 0 ms
   [watchman] command ["state-leave",{"metadata":{"path":"2"},"name":"hg.filemerge"}] finished in 0 ms
-  [watchman] command ["state-leave",{"metadata":{"distance":3,"merge":true,"partial":false,"rev":"65f3e88a53bc0f5183deea0cdbc46738777ec005","status":"ok"},"name":"hg.update"}] finished in 0 ms
+  [watchman] command ["state-leave",{"metadata":{"distance":2,"merge":true,"partial":false,"rev":"65f3e88a53bc0f5183deea0cdbc46738777ec005","status":"ok"},"name":"hg.update"}] finished in 0 ms
diff --git a/eden/scm/tests/test-log-simplify-grandparents.t b/eden/scm/tests/test-log-simplify-grandparents.t
index de72d4c3d4..55a411fdd9 100644
--- a/eden/scm/tests/test-log-simplify-grandparents.t
+++ b/eden/scm/tests/test-log-simplify-grandparents.t
@@ -1,5 +1,4 @@
 #debugruntest-compatible
-  $ setconfig format.use-segmented-changelog=1
   $ newrepo
   $ drawdag << 'EOS'
   > E
diff --git a/eden/scm/tests/test-segmented-changelog-rev-compat.t b/eden/scm/tests/test-segmented-changelog-rev-compat.t
index 2f1555ad03..6f6c1c81ca 100644
--- a/eden/scm/tests/test-segmented-changelog-rev-compat.t
+++ b/eden/scm/tests/test-segmented-changelog-rev-compat.t
@@ -1,7 +1,5 @@
 #debugruntest-compatible
 
-  $ setconfig format.use-segmented-changelog=1
-
   $ log_fixture() {
   >   newrepo '' "$@"
   >   drawdag "$@" << 'EOS'
diff --git a/eden/scm/tests/test-smartlog-collapse-obsolete.t b/eden/scm/tests/test-smartlog-collapse-obsolete.t
index efc24e260d..83c503d6d0 100644
--- a/eden/scm/tests/test-smartlog-collapse-obsolete.t
+++ b/eden/scm/tests/test-smartlog-collapse-obsolete.t
@@ -2,7 +2,6 @@
 #debugruntest-compatible
 
   $ configure modern
-  $ setconfig format.use-segmented-changelog=1
   $ enable smartlog rebase
   $ disable commitcloud
 
diff --git a/eden/scm/tests/test-smartlog-max-commit.t b/eden/scm/tests/test-smartlog-max-commit.t
index a0901cbbfd..fd0134ac8f 100644
--- a/eden/scm/tests/test-smartlog-max-commit.t
+++ b/eden/scm/tests/test-smartlog-max-commit.t
@@ -2,7 +2,6 @@
 #debugruntest-compatible
 
   $ configure modern
-  $ setconfig format.use-segmented-changelog=1
   $ enable smartlog rebase
   $ disable commitcloud
 
diff --git a/eden/scm/tests/test-template-revf64.t b/eden/scm/tests/test-template-revf64.t
index bc1730c186..94fdcbda85 100644
--- a/eden/scm/tests/test-template-revf64.t
+++ b/eden/scm/tests/test-template-revf64.t
@@ -1,5 +1,4 @@
   $ configure modern
-  $ setconfig format.use-segmented-changelog=1
 
   $ newrepo
   $ drawdag << 'EOS'
diff --git a/eden/testlib/tests.py b/eden/testlib/tests.py
index bd357a1935..c5d8823cb8 100644
--- a/eden/testlib/tests.py
+++ b/eden/testlib/tests.py
@@ -179,9 +179,9 @@ o  D
 │
 o    C
 ├─╮
-│ o  B
-│
-o  A
+o │  A
+  │
+  o  B
 
 """,
         )