For the second case:

network info catch update and there is port info for 375d726d-fccd-42e4-8b5f-60a200ed76af:

2014-09-21 05:27:06.976 DEBUG nova.network.base_api [req-d547ba16-49ec-468c-a2d3-00075880f33b TestNetworkBasicOps-1044489211 TestNetworkBasicOps-84164684] Updating cache with info: [VIF({'profile': {}, 'ovs_interfaceid': u'3725c51f-b240-404f-b747-06da1460126e', 'network': Network({'bridge': 'br-int', 'subnets': [Subnet({'ips': [FixedIP({'meta': {}, 'version': 4, 'type': 'fixed', 'floating_ips': [IP({'meta': {}, 'version': 4, 'type': 'floating', 'address': u'172.24.4.125'})], 'address': u'10.100.0.2'})], 'version': 4, 'meta': {'dhcp_server': u'10.100.0.3'}, 'dns': [], 'routes': [], 'cidr': u'10.100.0.0/28', 'gateway': IP({'meta': {}, 'version': 4, 'type': 'gateway', 'address': u'10.100.0.1'})})], 'meta': {'injected': False, 'tenant_id': u'9a48bc2e80124a6d9d0abfa0c53c908b'}, 'id': u'614ab449-b511-4e99-9694-121e33067d4c', 'label': u'network-smoke--545348394'}), 'devname': u'tap3725c51f-b2', 'vnic_type': u'normal', 'qbh_params': None, 'meta': {}, 'details': {u'port_filter': True, u'ovs_hybrid_plug': True}, 'address': u'fa:16:3e:e1:30:0f', 'active': True, 'type': u'ovs', 'id': u'3725c51f-b240-404f-b747-06da1460126e', 'qbg_params': None}), VIF({'profile': {}, 'ovs_interfaceid': u'375d726d-fccd-42e4-8b5f-60a200ed76af', 'network': Network({'bridge': 'br-int', 'subnets': [Subnet({'ips': [FixedIP({'meta': {}, 'version': 4, 'type': 'fixed', 'floating_ips': [], 'address': u'10.100.0.17'})], 'version': 4, 'meta': {'dhcp_server': u'10.100.0.18'}, 'dns': [], 'routes': [], 'cidr': u'10.100.0.16/28', 'gateway': IP({'meta': {}, 'version': None, 'type': 'gateway', 'address': None})})], 'meta': {'injected': False, 'tenant_id': u'9a48bc2e80124a6d9d0abfa0c53c908b'}, 'id': u'0e123907-7f88-47aa-a6d7-bbfc61105bff', 'label': u'network-smoke--29266327'}), 'devname': u'tap375d726d-fc', 'vnic_type': u'normal', 'qbh_params': None, 'meta': {}, 'details': {u'port_filter': True, u'ovs_hybrid_plug': True}, 'address': u'fa:16:3e:85:44:97', 'active': False, 'type': u'ovs', 'id': u'375d726d-fccd-42e4-8b5f-60a200ed76af', 'qbg_params': None})] update_instance_cache_with_nw_info 



And another network info catch update by _heal_instance_info_cache, but there isn't port info for 375d726d-fccd-42e4-8b5f-60a200ed76af:

2014-09-21 05:27:06.999 4710 DEBUG nova.network.base_api [-] Updating cache with info: [VIF({'profile': {}, 'ovs_interfaceid': u'3725c51f-b240-404f-b747-06da1460126e', 'network': Network({'bridge': 'br-int', 'subnets': [Subnet({'ips': [FixedIP({'meta': {}, 'version': 4, 'type': 'fixed', 'floating_ips': [IP({'meta': {}, 'version': 4, 'type': 'floating', 'address': u'172.24.4.125'})], 'address': u'10.100.0.2'})], 'version': 4, 'meta': {'dhcp_server': u'10.100.0.3'}, 'dns': [], 'routes': [], 'cidr': u'10.100.0.0/28', 'gateway': IP({'meta': {}, 'version': 4, 'type': 'gateway', 'address': u'10.100.0.1'})})], 'meta': {'injected': False, 'tenant_id': u'9a48bc2e80124a6d9d0abfa0c53c908b'}, 'id': u'614ab449-b511-4e99-9694-121e33067d4c', 'label': u'network-smoke--545348394'}), 'devname': u'tap3725c51f-b2', 'vnic_type': u'normal', 'qbh_params': None, 'meta': {}, 'details': {u'port_filter': True, u'ovs_hybrid_plug': True}, 'address': u'fa:16:3e:e1:30:0f', 'active': True, 'type': u'ovs', 'id': u'3725c51f-b240-404f-b747-06da1460126e', 'qbg_params': None})] update_instance_cache_with_nw_info /opt/stack/new/nova/nova/network/base_api.py:39
2014-09-21 05:27:07.010 4710 DEBUG nova.compute.manager [-] [instance: c65d83f5-db85-4adf-b8ae-bba2b81ac4c6] Updated the network info_cache for instance _heal_instance_info_cache /opt/stack/new/nova/nova/compute/manager.py:5311


This patch looks like fix similar problem: https://review.openstack.org/#/c/97662/