--- a/mercurial/context.py	Mon May 10 22:52:28 2010 +0200
+++ b/mercurial/context.py	Tue May 11 20:21:25 2010 +0200
@@ -724,7 +724,7 @@
         def findflag(ctx):
             mnode = ctx.changeset()[0]
             node, flag = self._repo.manifest.find(mnode, orig)
-            ff = self._repo.dirstate.flagfunc(lambda x: flag or None)
+            ff = self._repo.dirstate.flagfunc(lambda x: flag or '')
             try:
                 return ff(path)
             except OSError: