--- a/mercurial/hgweb.py
+++ b/mercurial/hgweb.py
@@ -965,7 +965,7 @@ class hgweb(object):
nodes = map(bin, req.form['roots'][0].split(" "))
z = zlib.compressobj()
- f = self.repo.changegroup(nodes)
+ f = self.repo.changegroup(nodes, 'serve')
while 1:
chunk = f.read(4096)
if not chunk: