bookmarks: reuse @number bookmark, if it refers changeset referred remotely

Before this patch, "@number" suffixed bookmark may be newly created at
each "hg pull" from the remote repository, if the bookmark in remote
repository diverges from one in local one.

This causes unexpected increase of "@number" suffixed bookmarks.

This patch reuses "@number" suffixed bookmark, if it refers the
changeset which is referred by the same bookmark in the remote
repository.

mercurial/bookmarks.py

@@ -362,11 +362,14 b' def compare(repo, srcmarks, dstmarks,'
 
     return results
 
-def _diverge(ui, b, path, localmarks):
+def _diverge(ui, b, path, localmarks, remotenode):
     '''Return appropriate diverged bookmark for specified ``path``
 
     This returns None, if it is failed to assign any divergent
     bookmark name.
+
+    This reuses already existing one with "@number" suffix, if it
+    refers ``remotenode``.
     '''
     if b == '@':
         b = ''
@@ -383,7 +386,7 b' def _diverge(ui, b, path, localmarks):'
     # assign a unique "@number" suffix newly
     for x in range(1, 100):
         n = '%s@%d' % (b, x)
-        if n not in localmarks:
+        if n not in localmarks or localmarks[n] == remotenode:
             return n
 
     return None
@@ -417,9 +420,10 b' def updatefromremote(ui, repo, remotemar'
             changed.append((b, bin(scid), status,
                             _("importing bookmark %s\n") % (b)))
         else:
-            db = _diverge(ui, b, path, localmarks)
+            snode = bin(scid)
+            db = _diverge(ui, b, path, localmarks, snode)
             if db:
-                changed.append((db, bin(scid), warn,
+                changed.append((db, snode, warn,
                                 _("divergent bookmark %s stored as %s\n") %
                                 (b, db)))
             else:

tests/test-bookmarks-pushpull.t

@@ -182,6 +182,24 b' divergent bookmarks'
   $ hg bookmarks | grep '^   X' | grep -v ':000000000000'
      X                         1:9b140be10808
      X@foo                     2:0d2164f0ce0d
+
+(test that remotely diverged bookmarks are reused if they aren't changed)
+
+  $ hg bookmarks | grep '^   @'
+     @                         1:9b140be10808
+     @1                        2:0d2164f0ce0d
+     @foo                      2:0d2164f0ce0d
+  $ hg pull ../a
+  pulling from ../a
+  searching for changes
+  no changes found
+  warning: failed to assign numbered name to divergent bookmark X
+  divergent bookmark @ stored as @1
+  $ hg bookmarks | grep '^   @'
+     @                         1:9b140be10808
+     @1                        2:0d2164f0ce0d
+     @foo                      2:0d2164f0ce0d
+
   $ python $TESTTMP/seq.py 1 100 | while read i; do hg bookmarks -d "X@${i}"; done
   $ hg bookmarks -d "@1"