[Twisted-Python] leakage between tests with trial when code under test uses deferToThread

Hi All, Does trial do anything to clean up stuff that's been passed to deferToThread? I'm seeing what looks like leakage between tests where stuff that is deferred to a thread from a LoopingCall is resulting in a DelayedCall ending up in the reactor for the next test. Does that ring any bells? cheers, Chris