--- a/mercurial/store.py	Wed Aug 15 12:04:50 2012 +0200
+++ b/mercurial/store.py	Wed Aug 15 16:30:32 2012 -0700
@@ -398,7 +398,7 @@
     def datafiles(self):
         rewrite = False
         existing = []
-        for f in self.fncache:
+        for f in sorted(self.fncache):
             ef = self.encode(f)
             try:
                 yield f, ef, self.getsize(ef)