Clean up callLaters

from twisted.internet import defer, reactor
from twisted.python import log
from twisted.trial.unittest import TestCase


class Tests(TestCase):
    timeout = 5

    def tearDown(self):
        log.msg("hi")

    def test_timeout(self):
        d = defer.Deferred()
        cl = reactor.callLater(self.timeout + 1, d.callback, None)
        self.addCleanup(cl.cancel)
        return d