mitsuhiko/flask-sqlalchemy — pull request #148 by malthe (2013-08-12 12:57:11+00:00)
Title: Use the 'sessionmaker' function as argument to 'scoped_session'.

As a result, it's no longer possible to provide a session object, but rather a session class, as a means of using a custom implementation:

def create_session_factory(self, options):
...

This fixes issue #147.