--- a/mercurial/context.py	Wed Jan 14 16:57:00 2015 -0800
+++ b/mercurial/context.py	Wed Jan 14 17:21:09 2015 -0800
@@ -49,7 +49,7 @@
             if path in ac[3]: # checking the 'files' field.
                 # The file has been touched, check if the content is similar
                 # to the one we search for.
-                if fnode == ma.readdelta(ac[0]).get(path):
+                if fnode == ma.readfast(ac[0]).get(path):
                     return a
         # In theory, we should never get out of that loop without a result. But
         # if manifest uses a buggy file revision (not children of the one it