diff -r 84fb29f5e0d2 -r eb07fbc21e9c mercurial/filemerge.py
--- a/mercurial/filemerge.py	Wed Jul 28 11:07:20 2010 +0200
+++ b/mercurial/filemerge.py	Tue Jul 27 23:40:46 2010 +0900
@@ -135,7 +135,7 @@
         except IOError:
             return False
 
-    if not fco.cmp(fcd.data()): # files identical?
+    if not fco.cmp(fcd): # files identical?
         return None
 
     if fca == fco: # backwards, use working dir parent as ancestor