Improve message when we check that we know all attributes

src/github/GitAuthor.py

@@ -31,7 +31,7 @@ class GitAuthor( object ):
     def __useAttributes( self, attributes ):
         # @todo Remove this debug weakness: we shall assume that github will add new attributes
         for attribute in attributes:
-            assert attribute in [ "date", "email", "name", ]
+            assert attribute in [ "date", "email", "name", ], attribute
         # @todo No need to check if attribute is in attributes when attribute is mandatory
         if "date" in attributes and attributes[ "date" ] is not None:
             assert isinstance( attributes[ "date" ], ( str, unicode ) )