mercurial/bookmarks.py

--- a/mercurial/bookmarks.py	Thu Dec 04 12:02:02 2014 -0500
+++ b/mercurial/bookmarks.py	Tue Dec 02 20:31:19 2014 -0800
@@ -79,6 +79,10 @@
         can be copied back on rollback.
         '''
         repo = self._repo
+        self._writerepo(repo)
+
+    def _writerepo(self, repo):
+        """Factored out for extensibility"""
         if repo._bookmarkcurrent not in self:
             unsetcurrent(repo)