'When canceling a L{Deferred} from a L{DeferredQueue} that already has
a result, the cancel should have no effect.'

def test_cancelQueueAfterSynchronousGet(self):

    def _failOnErrback(_):
        self.fail('Unexpected    errback    call!')
    queue = defer.DeferredQueue()
    d = queue.get()
    d.addErrback(_failOnErrback)
    queue.put(None)
    d.cancel()
