close all sqlalchemy sessions

[Stefano Rivera]

We need a bit of a SQLAlchemy usage audit

ERROR core.dispatcher: Exception occured in Identify processor of identity plugin
Traceback (most recent call last):
  File "/home/stefanor/projects/ibid/tibid/ibid/core.py", line 22, in _process
    processor.process(event)
  File "/home/stefanor/projects/ibid/tibid/ibid/plugins/identity.py", line 354, in process
    .filter(func.lower(Identity.identity) == event.sender['id'].lower())\
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/query.py", line 909, in first
    ret = list(self[0:1])
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/query.py", line 937, in __iter__
    self.session._autoflush()
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/session.py", line 771, in _autoflush
    self.flush()
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/session.py", line 789, in flush
    self.uow.flush(self, objects)
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/unitofwork.py", line 234, in flush
    session.create_transaction(autoflush=False)
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/session.py", line 502, in begin
    self.transaction = self.transaction._begin(**kwargs)
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/session.py", line 181, in _begin
    self._assert_is_active()
  File "/var/lib/python-support/python2.6/sqlalchemy/orm/session.py", line 169, in _assert_is_active
    raise exceptions.InvalidRequestError("The transaction is inactive due to a rollback in a subtransaction and should be closed")
InvalidRequestError: The transaction is inactive due to a rollback in a subtransaction and should be closed

I can reliably trigger that on tibid by connecting as a random user and saying "delete account tumbleweed" (he's running with identity-370434 and accounts-330942). However the bug doesn't appear to be in that code.

Here's some background: http://www.nabble.com/Transaction-problem-with-Oracle-%2B-SQLAlchemy-td15560443.html