diff -r a4191e0c728f -r 11e8fec00234 mercurial/context.py
--- a/mercurial/context.py	Sat Apr 11 16:01:42 2015 +0900
+++ b/mercurial/context.py	Thu Apr 09 22:18:55 2015 +0900
@@ -1191,6 +1191,8 @@
     def subrev(self, subpath):
         return None
 
+    def manifestnode(self):
+        return None
     def user(self):
         return self._user or self._repo.ui.username()
     def date(self):