--- a/mercurial/manifest.py	Wed Mar 11 13:46:15 2015 -0700
+++ b/mercurial/manifest.py	Thu Mar 12 18:53:44 2015 -0700
@@ -46,6 +46,9 @@
     def __iter__(self):
         return ((f, e[0], e[1]) for f, e in sorted(self.iteritems()))
 
+    def iterkeys(self):
+        return iter(sorted(dict.keys(self)))
+
     def copy(self):
         c = _lazymanifest('')
         c.update(self)