diff -r 18168938e1c1 -r c58432685cff mercurial/changegroup.py
--- a/mercurial/changegroup.py	Thu Oct 23 17:00:38 2014 -0700
+++ b/mercurial/changegroup.py	Fri Nov 07 17:54:59 2014 -0800
@@ -452,8 +452,8 @@
     def group(self, nodelist, revlog, lookup, units=None, reorder=None):
         if (revlog._generaldelta and reorder is not True):
             reorder = False
-        return cg1packer.group(self, nodelist, revlog, lookup,
-                               units=units, reorder=reorder)
+        return super(cg2packer, self).group(nodelist, revlog, lookup,
+                                            units=units, reorder=reorder)
 
     def deltaparent(self, revlog, rev, p1, p2, prev):
         dp = revlog.deltaparent(rev)