Change to list() per code review.

diff --git a/lib/sqlalchemy/orm/clsregistry.py b/lib/sqlalchemy/orm/clsregistry.py
index b78f4bdeea615085865e020736d22e782b82b151..bb062c5c981cc4f6402710a5bf3d82e09a469582 100644 (file)
--- a/lib/sqlalchemy/orm/clsregistry.py
+++ b/lib/sqlalchemy/orm/clsregistry.py
@@ -242,7 +242,7 @@ class _MultipleClassMarker(ClsRegistryToken):
         # [ticket:3208] and [ticket:10782]
         modules = {
             cls.__module__
-            for cls in [ref() for ref in self.contents.copy()]
+            for cls in [ref() for ref in list(self.contents)]
             if cls is not None
         }
         if item.__module__ in modules: