'L{defer.maybeDeferred} should let L{defer.Deferred} instance pass by
so that L{failure.Failure} returned by the original instance is the
same.'

def test_maybeDeferredAsyncError(self):

    d = defer.Deferred()
    d2 = defer.maybeDeferred((lambda : d))
    d.errback(failure.Failure(RuntimeError()))
    self.assertImmediateFailure(d2, RuntimeError)
