def tearDown(self):
        super(SimpleInstanceTest, self).tearDown()
        CONF.network_label_regex = self.orig_conf
        CONF.ip_start = None
def _try_write_with_flush(cls, fileobj, payload):
        """This method is here so that it can be patched to simulate write errors.

        This is because mock can't patch primitive objects like file objects.
        """
        fileobj.write(payload)
        fileobj.flush()