Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "nova/tests/unit/api/openstack/compute/test_flavors_extra_specs.py", line 69, in setUp
        super(FlavorsExtraSpecsTestV21, self).setUp()
      File "nova/test.py", line 215, in setUp
        self.useFixture(nova_fixtures.Database())
      File "nova/tests/fixtures.py", line 211, in __init__
        session.configure(CONF)
      File "nova/db/sqlalchemy/api.py", line 169, in configure
        main_context_manager.configure(**_get_db_conf(conf.database))
      File "/home/dan/nova/.tox/py27/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 625, in configure
        self._factory.configure(**kw)
      File "/home/dan/nova/.tox/py27/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 216, in configure
        self._configure(False, kw)
      File "/home/dan/nova/.tox/py27/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 221, in _configure
        raise TypeError("this TransactionFactory is already started")
    TypeError: this TransactionFactory is already started