diff -r 8d928799dab5 -r f6a737357195 mercurial/httprepo.py
--- a/mercurial/httprepo.py	Sun Jul 31 22:12:13 2011 +0200
+++ b/mercurial/httprepo.py	Mon Aug 01 10:54:34 2011 -0500
@@ -77,6 +77,7 @@
 
         if data and self.ui.configbool('ui', 'usehttp2', False):
             headers['Expect'] = '100-Continue'
+            headers['X-HgHttp2'] = '1'
 
         self.ui.debug("sending %s command\n" % cmd)
         q = [('cmd', cmd)]