'Handoff of a volume from A to B and then B to A between two ZFS-based
volume managers does not fail.'

def test_handoff_roundtrip(self):

    service_pair = create_realistic_servicepair(self)
    d = service_pair.from_service.create(service_pair.from_service.get(VolumeName(namespace=u'myns', dataset_id=u'myvolume')))
    def created(volume):
        return service_pair.from_service.handoff(volume, service_pair.remote)
    d.addCallback(created)
    def handed_off(_):
        return service_pair.to_service.handoff(service_pair.to_service.get(VolumeName(namespace=u'myns', dataset_id=u'myvolume')), service_pair.origin_remote)
    d.addCallback(handed_off)
    return d
