'If a Deferred with a failure result has an errback which chains it to
another Deferred, the initial failure is cleared by the errback so it is
not logged.'

def test_errorClearedByChaining(self):

    bad = defer.fail(Exception('oh    no'))
    good = defer.Deferred()
    bad.addErrback((lambda ignored: good))
    good = bad = None
    gc.collect()
    self.assertEqual(self._loggedErrors(), [])
