--- a/mercurial/url.py	Thu Jun 25 17:47:32 2015 -0500
+++ b/mercurial/url.py	Thu Jun 25 17:48:43 2015 -0500
@@ -469,6 +469,7 @@
     construct an opener suitable for urllib2
     authinfo will be added to the password manager
     '''
+    # experimental config: ui.usehttp2
     if ui.configbool('ui', 'usehttp2', False):
         handlers = [httpconnectionmod.http2handler(ui, passwordmgr(ui))]
     else: