--- a/mercurial/bundle2.py	Thu Apr 10 10:53:43 2014 -0700
+++ b/mercurial/bundle2.py	Mon Apr 14 14:46:32 2014 -0400
@@ -639,7 +639,7 @@
     # we need to make sure we trigger the creation of a transaction object used
     # for the whole processing scope.
     op.gettransaction()
-    cg = changegroup.readbundle(inpart, 'bundle2part')
+    cg = changegroup.unbundle10(inpart, 'UN')
     ret = changegroup.addchangegroup(op.repo, cg, 'bundle2', 'bundle2')
     op.records.add('changegroup', {'return': ret})
     if op.reply is not None: