diff -r 8f203b491bb5 -r e6eb86b154c5 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Fri Apr 22 21:45:06 2016 +0900
+++ b/mercurial/cmdutil.py	Fri Apr 22 21:46:33 2016 +0900
@@ -8,6 +8,7 @@
 from __future__ import absolute_import
 
 import errno
+import itertools
 import os
 import re
 import tempfile
@@ -1452,6 +1453,7 @@
             self.t = formatter.maketemplater(ui, 'changeset', tmpl,
                                              cache=defaulttempl)
 
+        self._counter = itertools.count()
         self.cache = {}
 
         # find correct templates for current mode
@@ -1490,6 +1492,7 @@
         props['ctx'] = ctx
         props['repo'] = self.repo
         props['ui'] = self.repo.ui
+        props['index'] = next(self._counter)
         props['revcache'] = {'copies': copies}
         props['cache'] = self.cache