--- a/mercurial/changegroup.py	Fri Jan 16 16:25:30 2015 -0800
+++ b/mercurial/changegroup.py	Thu Jan 15 14:39:41 2015 -0800
@@ -79,7 +79,7 @@
 # hgweb uses this list to communicate its preferred type
 bundlepriority = ['HG10GZ', 'HG10BZ', 'HG10UN']
 
-def writebundle(cg, filename, bundletype, vfs=None):
+def writebundle(ui, cg, filename, bundletype, vfs=None):
     """Write a bundle file and return its filename.
 
     Existing files will not be overwritten.