heat create complete but the vnf is in error status

https://github.com/openstack/tacker/blob/master/tacker/vnfm/infra_drivers/openstack/openstack.py#L138
        while status == 'CREATE_IN_PROGRESS' and stack_retries > 0:
            time.sleep(self.STACK_RETRY_WAIT)
            try:
                stack = heatclient.get(vnf_id)
            except Exception:
                LOG.exception(_("VNF Instance cleanup may not have "
                                "happened because Heat API request failed "
                                "while waiting for the stack %(stack)s to be "
                                "deleted"), {'stack': vnf_id})
                break
            status = stack.stack_status
            LOG.debug(_('status: %s'), status)
            stack_retries = stack_retries - 1

the error exception is:

2017-03-22 16:37:22.122 28787 ERROR tacker.vnfm.infra_drivers.openstack.openstack ConnectFailure: Unable to establish connection to http://310.xcodest.me:8004/v1/f3c6d500b267432c858c588800b49653/stacks/a5142d59-dcc6-43b1-b916-36d1f0426e73: ('Connection aborted.', BadStatusLine("''",))

this will cause vnf is in error status, but stack maybe complete.