Possible intermittent failure in juju.agents.tests.test_provision.FirewallManagerTest.test_watch_service_changes_is_called

Have seen this in two test suite runs of juju:

[FAIL]
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1020, in _inlineCallbacks
    result = g.send(result)
  File "/build/buildd/juju-0.5+bzr494/juju/agents/tests/test_provision.py", line 522, in test_watch_service_changes_is_called
    (set(["mysql", "wordpress"]), set(["wordpress"]))])
twisted.trial.unittest.FailTest: not equal:
a = [(set(), set(['wordpress'])),
 (set(['wordpress']), set(['mysql', 'wordpress']))]
b = [(set(), set(['wordpress'])),
 (set(['wordpress']), set(['mysql', 'wordpress'])),
 (set(['mysql', 'wordpress']), set(['wordpress']))]

juju.agents.tests.test_provision.FirewallManagerTest.test_watch_service_changes_is_called

Re-running usually succeeds, so I think this test may have a race condition in it.