Comment 2 for bug 1855015

Also note that the majority of jobs here aren't failing:

http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22Multiple%20possible%20networks%20found%2C%20use%20a%20Network%20ID%20to%20be%20more%20specific%5C%22%20AND%20tags%3A%5C%22screen-n-api.txt%5C%22%20AND%20build_name%3A%5C%22nova-next%5C%22%20AND%20build_queue%3A%5C%22gate%5C%22&from=7d

which indicates the error is coming from a negative test. It looks like it's this one:

2019-12-03 19:31:28.495 2944 INFO tempest.lib.common.rest_client [req-c0140b95-56dd-4376-ad0c-49a05a778cc4 ] Request (AttachInterfacesTestJSON:test_create_list_show_delete_interfaces_by_network_port): 400 POST https://10.209.32.173/compute/v2.1/servers/36bbc9fb-1453-4813-bdf5-c2ae59de6a75/os-interface 0.528s
2019-12-03 19:31:28.495 2944 DEBUG tempest.lib.common.rest_client [req-c0140b95-56dd-4376-ad0c-49a05a778cc4 ] Request - Headers: {'Content-Type': 'application/json', 'Accept': 'application/json', 'X-Auth-Token': '<omitted>'}
        Body: {"interfaceAttachment": {}}
    Response - Headers: {'date': 'Tue, 03 Dec 2019 19:31:27 GMT', 'server': 'Apache/2.4.29 (Ubuntu)', 'openstack-api-version': 'compute 2.1', 'x-openstack-nova-api-version': '2.1', 'vary': 'OpenStack-API-Version,X-OpenStack-Nova-API-Version', 'content-type': 'application/json; charset=UTF-8', 'content-length': '115', 'x-openstack-request-id': 'req-c0140b95-56dd-4376-ad0c-49a05a778cc4', 'x-compute-request-id': 'req-c0140b95-56dd-4376-ad0c-49a05a778cc4', 'connection': 'close', 'status': '400', 'content-location': 'https://10.209.32.173/compute/v2.1/servers/36bbc9fb-1453-4813-bdf5-c2ae59de6a75/os-interface'}
        Body: b'{"badRequest": {"code": 400, "message": "Multiple possible networks found, use a Network ID to be more specific."}}' _log_request_full /opt/stack/tempest/tempest/lib/common/rest_client.py:440