- add event.contains() function to the event package, returns True

if the given target/event/fn is set up to listen.
- repair mutable package which is doing some conditional event listening

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/sqlalchemy/ext/mutable.py b/lib/sqlalchemy/ext/mutable.py
index d3133b1f5..5458de381 100644
--- a/lib/sqlalchemy/ext/mutable.py
+++ b/lib/sqlalchemy/ext/mutable.py
@@ -595,7 +595,7 @@ def _setup_composite_listener():
                  issubclass(prop.composite_class, MutableComposite)):
                 prop.composite_class._listen_on_attribute(
                     getattr(class_, prop.key), False, class_)
-    if not Mapper.dispatch.mapper_configured._contains(Mapper, _listen_for_type):
+    if not event.contains(Mapper, "mapper_configured", _listen_for_type):
         event.listen(Mapper, 'mapper_configured', _listen_for_type)
 _setup_composite_listener()