'The ``DELETE`` action on an already ``deleted`` dataset has same
response as original deletion.'

def test_delete_idempotent(self):

    created = self._setup_manifestation()
    def got_manifestation(expected_manifestation):
        d = self._test_delete(expected_manifestation.dataset)
        d.addCallback((lambda _: self._test_delete(expected_manifestation)))
        return d
    created.addCallback(got_manifestation)
    return created
