diff -r 521b4d061d4a -r a5f5a815a006 mercurial/changegroup.py
--- a/mercurial/changegroup.py	Fri Sep 11 17:05:46 2015 -0700
+++ b/mercurial/changegroup.py	Fri Sep 11 17:06:02 2015 -0700
@@ -570,7 +570,7 @@
 
 def getsubset(repo, outgoing, bundler, source, fastpath=False, version='01'):
     gengroup = getsubsetraw(repo, outgoing, bundler, source, fastpath)
-    return packermap[version][1](util.chunkbuffer(gengroup), 'UN')
+    return packermap[version][1](util.chunkbuffer(gengroup), None)
 
 def changegroupsubset(repo, roots, heads, source, version='01'):
     """Compute a changegroup consisting of all the nodes that are