diff -r e245775f8fd3 -r b01c491af0cf mercurial/changelog.py
--- a/mercurial/changelog.py	Wed Nov 05 10:22:17 2014 +0000
+++ b/mercurial/changelog.py	Sat Nov 08 16:27:50 2014 +0000
@@ -270,7 +270,7 @@
         self._nodecache = r._nodecache
         self._chunkcache = r._chunkcache
 
-    def _writepending(self):
+    def _writepending(self, tr):
         "create a file containing the unfinalized state for pretxnchangegroup"
         if self._delaybuf:
             # make a temporary copy of the index