magic-removal: Changed AutoField.contribute_to_class() to use 'assert…

…' instead of 'if'

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@2027 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/__init__.py

@@ -345,8 +345,7 @@ def get_manipulator_new_data(self, new_data, rel=False):
         return Field.get_manipulator_new_data(self, new_data, rel)
 
     def contribute_to_class(self, cls, name):
-        if cls._meta.has_auto_field:
-            raise AssertionError, "A model can't have more than one AutoField."
+        assert not cls._meta.has_auto_field, "A model can't have more than one AutoField."
         super(AutoField, self).contribute_to_class(cls, name)
         cls._meta.has_auto_field = True