make sure _trans_subject in __exit__ always has a value

diff --git a/lib/sqlalchemy/engine/util.py b/lib/sqlalchemy/engine/util.py
index 32b59e8e604c685e15c16d022e33e3b1c8be99d9..f74cd3f8471ea9f00e46aed08ff3a976b7bc461d 100644 (file)
--- a/lib/sqlalchemy/engine/util.py
+++ b/lib/sqlalchemy/engine/util.py
@@ -95,7 +95,7 @@ class TransactionalContext:
         return self
 
     def __exit__(self, type_, value, traceback):
-        subject = self._trans_subject
+        subject = getattr(self, "_trans_subject", None)
 
         # simplistically we could assume that
         # "subject._trans_context_manager is self".  However, any calling