scmprompt: output only one remote bookmark

Summary:
Recently I had this scm prompt:
{F64910275}

This is not user friendly. I suggest to output at most one remote bookmark

Also this diff copies `seq.py` from upstream hg repo

Test Plan: Run scm prompt tests on devserver and mac and with '--shell=zsh'

Reviewers: rmcelroy

Reviewed By: rmcelroy

Subscribers: simonfar, wez, mjpieters, #sourcecontrol

Differential Revision: https://phabricator.intern.facebook.com/D4197242

Signature: t1:4197242:1483466446:cd1fe943dc99fde0600a4e20994fa4b0f971f72a

scripts/scm-prompt.sh

@@ -51,6 +51,24 @@
 # =========================================================================
 #
 
+_find_most_relevant_remotebookmark()
+{
+    # We don't want to output all remote bookmarks because there can be many
+    # of them. This function finds the most relevant remote bookmark using this
+    # algorithm:
+    # 1. If 'master' or '@' bookmark is available then output it
+    # 2. Sort remote bookmarks and output the first in reverse sorted order (
+    # it's a heuristic that tries to find the newest bookmark. It will work well
+    # with bookmarks like 'release20160926' and 'release20161010').
+    relevantbook=$(command grep -m1 -E -o "^[^/]+/(master|@)$" <<< "$1")
+    if [[ -n $relevantbook ]]; then
+        command echo $relevantbook
+        return 0
+    fi
+
+    command echo "$(command sort -r <<< "$1" | command head -n 1)"
+}
+
 _scm_prompt()
 {
   local dir git hg fmt
@@ -115,10 +133,14 @@ _scm_prompt()
     fi
     local remote="$hg/.hg/remotenames"
     if [[ -f "$remote" ]]; then
-      local marks=$(command grep "^$dirstate bookmarks" "$remote" | \
-        command cut -f 3 -d ' ' | command tr '\n' '|' | command sed -e 's/|$//')
-      if [[ -n "$marks" ]]; then
-        br="$br|$marks"
+      local allremotemarks="$(command grep "^$dirstate bookmarks" "$remote" | \
+        command cut -f 3 -d ' ')"
+
+      if [[ -n "$allremotemarks" ]]; then
+          local remotemark="$(_find_most_relevant_remotebookmark "$allremotemarks")"
+          if [[ -n "$remotemark" ]]; then
+            br="$br|$remotemark..."
+          fi
       fi
     fi
     local branch

tests/seq.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+#
+# A portable replacement for 'seq'
+#
+# Usage:
+#   seq STOP              [1, STOP] stepping by 1
+#   seq START STOP        [START, STOP] stepping by 1
+#   seq START STEP STOP   [START, STOP] stepping by STEP
+
+from __future__ import absolute_import, print_function
+import sys
+
+start = 1
+if len(sys.argv) > 2:
+    start = int(sys.argv[1])
+
+step = 1
+if len(sys.argv) > 3:
+    step = int(sys.argv[2])
+
+stop = int(sys.argv[-1]) + 1
+
+for i in xrange(start, stop, step):
+    print(i)

tests/test-scm-prompt-hg.t

@@ -156,7 +156,7 @@ Test remotenames
   4b6cc7d5194bd5dbf63970015ec75f8fd1de6dba
   $ echo 4b6cc7d5194bd5dbf63970015ec75f8fd1de6dba bookmarks remote/@ > .hg/remotenames
   $ cmd
-  (4b6cc7d|remote/@)
+  (4b6cc7d|remote/@...)
 
 Test shared bookmarks
   $ cmd cd ..
@@ -190,7 +190,7 @@ Test branches
   $ cmd hg branch blah
   marked working directory as branch blah
   (branches are permanent and global, did you want a bookmark?)
-  (4b6cc7d|remote/@|blah)
+  (4b6cc7d|remote/@...|blah)
   $ cmd hg commit -m blah
   (a742469|blah)
   $ cmd hg up -q default
@@ -230,3 +230,18 @@ Test formatting options
    97af35b 
   $ _scm_prompt ':%s:'
   :97af35b: (no-eol)
+
+Test many remotenames
+  $ hg log -r . -T '{node}\n'
+  97af35b3648c0098cbd8114ae1b1bafab997ac20
+  $ for i in `python $TESTDIR/seq.py 1 10`; do
+  > echo 97af35b3648c0098cbd8114ae1b1bafab997ac20 bookmarks remote/remote$i >> .hg/remotenames
+  > done
+  $ cmd
+  (97af35b|remote/remote9...)
+  $ echo 97af35b3648c0098cbd8114ae1b1bafab997ac20 bookmarks remote/abc/master >> .hg/remotenames
+  $ cmd
+  (97af35b|remote/remote9...)
+  $ echo 97af35b3648c0098cbd8114ae1b1bafab997ac20 bookmarks remote/@ >> .hg/remotenames
+  $ cmd
+  (97af35b|remote/@...)