Fixed #13428 -- Corrected the allow_relation behavior of and example router.…

Fixed #13428 -- Corrected the allow_relation behavior of and example router. Thanks to jcd for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13133 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/topics/db/multi-db.txt

@@ -256,7 +256,7 @@ master/slave relationship between the databases ``master``, ``slave1`` and
         def allow_relation(self, obj1, obj2, **hints):
             "Allow any relation between two objects in the db pool"
             db_list = ('master','slave1','slave2')
-            if obj1 in db_list and obj2 in db_list:
+            if obj1._state.db in db_list and obj2._state.db in db_list:
                 return True
             return None