avoid unnecessary mapper.extension copy

diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index bec6f1c3eba59cb8bb369e00ffcac76e5bf29b2b..ab31b328bfe59d0fc40c68c7af25f4d437539950 100644 (file)
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -43,7 +43,7 @@ class Query(object):
 
         self._with_options = []
         self._lockmode = None
-        self._extension = self.mapper.extension.copy()
+        self._extension = self.mapper.extension
         self._entities = []
         self._order_by = False
         self._group_by = False