--- a/mercurial/exchange.py	Mon Apr 06 15:40:12 2015 -0700
+++ b/mercurial/exchange.py	Mon Apr 06 16:04:33 2015 -0700
@@ -33,7 +33,7 @@
             alg = changegroup.readexactly(fh, 2)
         return changegroup.cg1unpacker(fh, alg)
     elif version == '2Y':
-        return bundle2.unbundle20(ui, fh, header=magic + version)
+        return bundle2.getunbundler(ui, fh, header=magic + version)
     else:
         raise util.Abort(_('%s: unknown bundle version %s') % (fname, version))