- initial MySQL Connector/Python driver

- support exceptions raised in dialect initialize phase
- provide default dialect create_connect_args() method

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index 829f97558..643faa982 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -880,7 +880,9 @@ class Connection(Connectable):
             raise
 
     def _rollback_impl(self):
-        if not self.closed and not self.invalidated and self.__connection.is_valid:
+        # use getattr() for is_valid to support exceptions raised in dialect initializer, 
+        # where we do not yet have the pool wrappers plugged in
+        if not self.closed and not self.invalidated and getattr(self.__connection, 'is_valid', False):
             if self.engine._should_log_info:
                 self.engine.logger.info("ROLLBACK")
             try: