merge: let manifestmerge emit 'keep' actions when keeping wd version

Such a 'keep' action will later be the preferred (non)action when there
is multiple ancestors. It is thus very convenient to have it explicitly.

The extra actions will only be emitted in the case where the local file has
changed since the ancestor but the other hasn't. That is the symmetrical
operation to a 'get' action.

This will create more action tuples that not really serve a purpose. The number
of actions will however have the number of changed files as upper bound and it
should thus not increase the memory/cpu use significantly.

mercurial/merge.py

@@ -449,7 +449,7 @@ def manifestmerge(repo, wctx, p2, pa, branchmerge, force, partial,
             fla = ma.flags(fa)
             nol = 'l' not in fl1 + fl2 + fla
             if n2 == a and fl2 == fla:
-                pass # remote unchanged - keep local
+                actions.append((f, "k", (), "keep")) # remote unchanged
             elif n1 == a and fl1 == fla: # local unchanged - use remote
                 if n1 == n2: # optimization: keep local content
                     actions.append((f, "e", (fl2,), "update permissions"))
@@ -634,13 +634,13 @@ def applyupdates(repo, actions, wctx, mctx, overwrite):
             audit(f)
             util.unlinkpath(repo.wjoin(f))
 
-    numupdates = len(actions)
+    numupdates = len([a for a in actions if a[1] != 'k'])
     workeractions = [a for a in actions if a[1] in 'gr']
     updateactions = [a for a in workeractions if a[1] == 'g']
     updated = len(updateactions)
     removeactions = [a for a in workeractions if a[1] == 'r']
     removed = len(removeactions)
-    actions = [a for a in actions if a[1] not in 'gr']
+    actions = [a for a in actions if a[1] not in 'grk']
 
     hgsub = [a[1] for a in workeractions if a[0] == '.hgsubstate']
     if hgsub and hgsub[0] == 'r':
@@ -778,6 +778,8 @@ def recordupdates(repo, actions, branchmerge):
             repo.dirstate.drop(f)
         elif m == "e": # exec change
             repo.dirstate.normallookup(f)
+        elif m == "k": # keep
+            pass
         elif m == "g": # get
             if branchmerge:
                 repo.dirstate.otherparent(f)

tests/test-graft.t

@@ -150,6 +150,7 @@ Graft out of order, skipping a merge and a duplicate
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 4c60f11aa304, local: 6b9e5368ca4e+, remote: 97f8bfe72746
+   b: keep -> k
    e: remote is newer -> g
   getting e
   updating: e 1/1 files (100.00%)
@@ -159,6 +160,7 @@ Graft out of order, skipping a merge and a duplicate
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 4c60f11aa304, local: 1905859650ec+, remote: 9c233e8e184d
+   b: keep -> k
    d: remote is newer -> g
    e: versions differ -> m
     preserving e for resolve of e

tests/test-issue672.t

@@ -36,6 +36,7 @@ http://mercurial.selenic.com/bts/issue672
    ancestor: 81f4b099af3d, local: c64f439569a9+, remote: c12dcd37c90a
    1: other deleted -> r
    1a: remote created -> g
+   2: keep -> k
   removing 1
   updating: 1 1/2 files (50.00%)
   getting 1a

tests/test-rename-merge2.t

@@ -86,6 +86,7 @@ $4 = expected result
   resolving manifests
    branchmerge: True, force: False, partial: False
    ancestor: 924404dff337, local: e300d1c794ec+, remote: 4ce40f5aca24
+   a: keep -> k
    b: remote copied from a -> m
     preserving a for resolve of b
    rev: versions differ -> m
@@ -570,6 +571,7 @@ m "um a c" "um x c" "      " "10 do merge with no ancestor"
   resolving manifests
    branchmerge: True, force: False, partial: False
    ancestor: 924404dff337, local: 0b76e65c8289+, remote: 4ce40f5aca24
+   a: keep -> k
    b: versions differ -> m
     preserving b for resolve of b
    rev: versions differ -> m