Comment 1 for bug 1291047

Bug is likely triggered by this code in SQL Alchemy:

This seems as related to eventlet/tpool etc issues, here with SQLAlchemy.
For example like https://bitbucket.org/eventlet/eventlet/issue/118/exceptions-are-cleared-during

pattern is seen here
sqlalchemy/orm/session.py

 442 def __exit__(self, type, value, traceback):
 443 self._assert_is_open("Cannot end transaction context. The transaction "
 444 "was closed from within the context")
 445 if self.session.transaction is None:
 446 return
 447 if type is None:
 448 try:
 449 self.commit()
 450 except:
 451 self.rollback()
 452 raise
 453 else:
 454 self.rollback()