--- a/mercurial/changegroup.py	Wed Aug 25 16:53:06 2010 -0500
+++ b/mercurial/changegroup.py	Wed Aug 25 16:55:54 2010 -0500
@@ -141,6 +141,9 @@
 class unbundle10(object):
     def __init__(self, fh, alg):
         self._stream = util.chunkbuffer(decompressor(fh, alg))
+        self._type = alg
+    def compressed(self):
+        return self._type != 'UN'
     def read(self, l):
         return self._stream.read(l)