--- a/tracext/hg/backend.py	Thu Feb 06 14:44:05 2014 +0900
+++ b/tracext/hg/backend.py	Thu Feb 06 20:55:32 2014 +0100
@@ -21,6 +21,7 @@
 import posixpath
 import re
 import sys
+import types
 
 import pkg_resources
 
@@ -155,13 +156,13 @@
             return get_bookmarks(ctx)
     return ()
 
-# Note: localrepository.branchtags deleated in mercurial-2.9.
-# see http://selenic.com/hg/rev/4274eda143cb
+# Note: localrepository.branchtags was removed in mercurial-2.9
+#       see http://selenic.com/hg/rev/4274eda143cb
 def get_branchtags(repo):
-    '''return a dict where branch names map to the tipmost head of
-    the branch, open heads come before closed'''
-
-    def branchtip(repo, heads):
+    """return a dict where branch names map to the tipmost head of
+    the branch, open heads come before closed_branches
+    """
+    def branchtip(heads):
         '''return the tipmost branch head in heads'''
         tip = heads[-1]
         for h in reversed(heads):
@@ -172,7 +173,7 @@
 
     bt = {}
     for bn, heads in repo.branchmap().iteritems():
-        bt[bn] = branchtip(repo, heads)
+        bt[bn] = branchtip(heads)
     return bt
 
 class trac_ui(ui):
@@ -473,7 +474,7 @@
                 repos = rm.get_repository(reponame)
             if repos:
                 if ns == 'branch':
-                    for b, n in get_branchtags(repos.repo).items():
+                    for b, n in repos.repo.branchtags().items():
                         if repos.to_u(b) == rev:
                             rev = repos.repo.changelog.rev(n)
                             break
@@ -566,6 +567,9 @@
                               " repository (Mercurial %(version)s says "
                               "%(error)s)",
                               path=path, version=version, error=error))
+        # restore branchtags() if needed (see StackOverflow:972)
+        if not getattr(self.repo, 'branchtags', None):
+            self.repo.branchtags = types.MethodType(get_branchtags, self.repo)
         Repository.__init__(self, 'hg:%s' % path, params, log)
 
     def from_hg_time(self, timeinfo):
@@ -636,7 +640,7 @@
         # map ctx to (unicode) branch
         branches = {}
         closed_branches = {}
-        for b, n in get_branchtags(self.repo).items():
+        for b, n in self.repo.branchtags().items():
             b = self.to_u(b)
             ctx = self.repo[n]
             if 'close' in ctx.extra():