diff -r 37cccad55410 -r 953839de96ab mercurial/bundle2.py
--- a/mercurial/bundle2.py	Sun Jul 17 15:10:30 2016 -0700
+++ b/mercurial/bundle2.py	Sun Jul 17 15:13:51 2016 -0700
@@ -1294,6 +1294,9 @@
         bundle.setcompression(compression)
         part = bundle.newpart('changegroup', data=cg.getchunks())
         part.addparam('version', cg.version)
+        if 'clcount' in cg.extras:
+            part.addparam('nbchanges', str(cg.extras['clcount']),
+                          mandatory=False)
         chunkiter = bundle.getchunks()
     else:
         # compression argument is only for the bundle2 case