diff -r ffec6d0a5ed6 -r 203b7a759218 mercurial/scmutil.py
--- a/mercurial/scmutil.py	Tue Jan 01 12:50:46 2013 -0600
+++ b/mercurial/scmutil.py	Tue Jan 01 12:51:00 2013 -0600
@@ -959,4 +959,4 @@
         try:
             del obj.__dict__[self.name]
         except KeyError:
-            raise AttributeError, self.name
+            raise AttributeError(self.name)