diff -r 47a12de9ac3f -r 83d82fbefccb mercurial/changegroup.py
--- a/mercurial/changegroup.py	Thu Oct 01 19:14:33 2015 -0700
+++ b/mercurial/changegroup.py	Thu Oct 01 19:14:47 2015 -0700
@@ -645,7 +645,8 @@
         heads = cl.heads()
     return discovery.outgoing(cl, common, heads)
 
-def getchangegroup(repo, source, heads=None, common=None, bundlecaps=None):
+def getchangegroup(repo, source, heads=None, common=None, bundlecaps=None,
+                   version='01'):
     """Like changegroupsubset, but returns the set difference between the
     ancestors of heads and the ancestors common.
 
@@ -655,7 +656,8 @@
     current discovery protocol works.
     """
     outgoing = computeoutgoing(repo, heads, common)
-    return getlocalchangegroup(repo, source, outgoing, bundlecaps=bundlecaps)
+    return getlocalchangegroup(repo, source, outgoing, bundlecaps=bundlecaps,
+                               version=version)
 
 def changegroup(repo, basenodes, source):
     # to avoid a race we use changegroupsubset() (issue1320)