Race in deleting ports during Tempest Runs

[Sean Dague]

This is similar to https://bugs.launchpad.net/tempest/+bug/1357055 which is closed (and honestly would be confusing to make this the same bug).

When trying to tear down subnets, they sometimes fail because the port still exists. However there is no indication that the port delete failed.

2017-06-05 18:38:20.846777 | Captured traceback-1:
2017-06-05 18:38:20.846795 | ~~~~~~~~~~~~~~~~~~~~~
2017-06-05 18:38:20.846817 | Traceback (most recent call last):
2017-06-05 18:38:20.846853 | File "tempest/lib/common/utils/test_utils.py", line 84, in call_and_ignore_notfound_exc
2017-06-05 18:38:20.846890 | return func(*args, **kwargs)
2017-06-05 18:38:20.846926 | File "tempest/lib/services/network/subnets_client.py", line 52, in delete_subnet
2017-06-05 18:38:20.846949 | return self.delete_resource(uri)
2017-06-05 18:38:20.846981 | File "tempest/lib/services/network/base.py", line 41, in delete_resource
2017-06-05 18:38:20.847004 | resp, body = self.delete(req_uri)
2017-06-05 18:38:20.847034 | File "tempest/lib/common/rest_client.py", line 301, in delete
2017-06-05 18:38:20.847064 | return self.request('DELETE', url, extra_headers, headers, body)
2017-06-05 18:38:20.847094 | File "tempest/lib/common/rest_client.py", line 659, in request
2017-06-05 18:38:20.847117 | self._error_checker(resp, resp_body)
2017-06-05 18:38:20.847149 | File "tempest/lib/common/rest_client.py", line 780, in _error_checker
2017-06-05 18:38:20.847175 | raise exceptions.Conflict(resp_body, resp=resp)
2017-06-05 18:38:20.847208 | tempest.lib.exceptions.Conflict: An object with that identifier already exists
2017-06-05 18:38:20.847274 | Details: {u'detail': u'', u'message': u'Unable to complete operation on subnet 276de24c-4560-47f5-9feb-2964314d7814: One or more ports have an IP allocation from this subnet.', u'type': u'SubnetInUse'}

http://logs.openstack.org/53/469253/1/gate/gate-tempest-dsvm-neutron-linuxbridge-ubuntu-xenial/64416cc/console.html#_2017-06-05_18_38_20_847274

[Hirofumi Ichihara (ichihara-hirofumi)]

32 hits for 24h :(

http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22One%20or%20more%20ports%20have%20an%20IP%20allocation%20from%20this%20subnet%5C%22%20AND%20filename%3A%20%5C%22console.html%5C%22%20AND%20build_name%3A%20%5C%22gate-tempest-dsvm-neutron-linuxbridge-ubuntu-xenial%5C%22