bookmarks: prevent divergent bookmark from being updated unexpectedly

bookmarks: prevent divergent bookmark from being updated unexpectedly

Before this patch, "@99" suffixed bookmark may be updated unexpectedly
by the bookmark value on the remote side at "hg pull", if all of "@1"
to "@99" suffixed bookmarks exist in the local repository, because
variable "n" still refers "@99" suffixed bookmark after the loop to
examine "@num" suffixes, even though it already exists in the local
repository.

This patch prevents divergent bookmark from being updated
unexpectedly, and shows warning message in such situation.

This patch uses original python script "seq.py" instead of "seq"
command to create sequence numbers in the test, because "seq" command
may not be available: it isn't defined in recent POSIX specification
(POSIX.1-2001 2013 Edition or XPG7)

--- a/mercurial/bookmarks.py	Wed Mar 18 11:41:36 2015 -0700
+++ b/mercurial/bookmarks.py	Tue Mar 17 18:20:24 2015 +0900
@@ -363,6 +363,11 @@
     return results
 
 def _diverge(ui, b, path, localmarks):
+    '''Return appropriate diverged bookmark for specified ``path``
+
+    This returns None, if it is failed to assign any divergent
+    bookmark name.
+    '''
     if b == '@':
         b = ''
     # find a unique @ suffix
@@ -370,6 +375,8 @@
         n = '%s@%d' % (b, x)
         if n not in localmarks:
             break
+    else:
+        n = None
     # try to use an @pathalias suffix
     # if an @pathalias already exists, we overwrite (update) it
     if path.startswith("file:"):
@@ -411,9 +418,13 @@
                             _("importing bookmark %s\n") % (b)))
         else:
             db = _diverge(ui, b, path, localmarks)
-            changed.append((db, bin(scid), warn,
-                            _("divergent bookmark %s stored as %s\n")
-                            % (b, db)))
+            if db:
+                changed.append((db, bin(scid), warn,
+                                _("divergent bookmark %s stored as %s\n") %
+                                (b, db)))
+            else:
+                warn(_("warning: failed to assign numbered name "
+                       "to divergent bookmark %s\n") % (b))
     for b, scid, dcid in adddst + advdst:
         if b in explicit:
             explicit.discard(b)

--- a/tests/test-bookmarks-pushpull.t	Wed Mar 18 11:41:36 2015 -0700
+++ b/tests/test-bookmarks-pushpull.t	Tue Mar 17 18:20:24 2015 +0900
@@ -164,6 +164,27 @@
      Z                         2:0d2164f0ce0d
      foo                       -1:000000000000
    * foobar                    1:9b140be10808
+
+(test that too many divergence of bookmark)
+
+  $ cat > $TESTTMP/seq.py <<EOF
+  > import sys
+  > for i in xrange(*[int(a) for a in sys.argv[1:]]):
+  >     print i
+  > EOF
+  $ python $TESTTMP/seq.py 1 100 | while read i; do hg bookmarks -r 000000000000 "X@${i}"; done
+  $ 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 '^   X' | grep -v ':000000000000'
+     X                         1:9b140be10808
+     X@foo                     2:0d2164f0ce0d
+  $ python $TESTTMP/seq.py 1 100 | while read i; do hg bookmarks -d "X@${i}"; done
+  $ hg bookmarks -d "@1"
+
   $ hg push -f ../a
   pushing to ../a
   searching for changes