--- a/mercurial/changegroup.py	Tue Apr 01 14:40:35 2014 -0700
+++ b/mercurial/changegroup.py	Tue Apr 01 15:08:27 2014 -0700
@@ -510,3 +510,7 @@
     outgoing = discovery.outgoing(cl, common, heads)
     return getlocalbundle(repo, source, outgoing, bundlecaps=bundlecaps)
 
+def changegroup(repo, basenodes, source):
+    # to avoid a race we use changegroupsubset() (issue1320)
+    return changegroupsubset(repo, basenodes, repo.heads(), source)
+