diff -r 1659549870e1 -r d34cf260d15b mercurial/wireproto.py
--- a/mercurial/wireproto.py	Sun Sep 25 13:20:55 2016 -0700
+++ b/mercurial/wireproto.py	Sun Sep 25 12:20:31 2016 -0700
@@ -78,10 +78,11 @@
     #    """
     #    raise NotImplementedError()
 
-    def groupchunks(self, cg):
-        """return 4096 chunks from a changegroup object
+    def groupchunks(self, fh):
+        """Generator of chunks to send to the client.
 
-        Some protocols may have compressed the contents."""
+        Some protocols may have compressed the contents.
+        """
         raise NotImplementedError()
 
 class remotebatch(peer.batcher):