tap interface in OVS is not removed after service removed in Swarm mode

[Hyunsun Moon]

Reproduce step

1. create a service with Kuryr driver network and checks Neutron ports are created for the service

$ neutron port-list
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
+-----------------------------------+-----------------------------------+----------------------------------+-------------------+--------------------------------------+
| id | name | tenant_id | mac_address | fixed_ips |
+-----------------------------------+-----------------------------------+----------------------------------+-------------------+--------------------------------------+
| 299a12ef-99dd-452a- | | 669ad66d0f7b427794603de2a2654579 | fa:16:3e:47:39:35 | {"subnet_id": "70613cf3-7894-4096-af |
| bce8-e74a69ef0a24 | | | | 45-c2f9718ca2fb", "ip_address": |
| | | | | "192.168.0.6"} |
| 339c7192-270b-4724-92dd- | | 669ad66d0f7b427794603de2a2654579 | fa:16:3e:7d:aa:27 | {"subnet_id": "70613cf3-7894-4096-af |
| cde87a4e1c59 | | | | 45-c2f9718ca2fb", "ip_address": |
| | | | | "192.168.0.2"} |
| 648e4034-c01a-4ec8-93ef- | ee99c3fb74ea535e0041ba8694093fa1b | 669ad66d0f7b427794603de2a2654579 | fa:16:3e:fd:4c:22 | {"subnet_id": "70613cf3-7894-4096-af |
| 7f9be4fd6ab3 | 93ec4fc685caab349172cdc5730c3a3-p | | | 45-c2f9718ca2fb", "ip_address": |
| | ort | | | "192.168.0.7"} |
| b0ecc74c-44cf-4f3d- | kuryr-unbound-port | 669ad66d0f7b427794603de2a2654579 | fa:16:3e:04:85:00 | {"subnet_id": "70613cf3-7894-4096-af |
| 9fd4-d1ac2fbf785a | | | | 45-c2f9718ca2fb", "ip_address": |
| | | | | "192.168.0.12"} |
+-----------------------------------+-----------------------------------+----------------------------------+-------------------+--------------------------------------+

2. also checks qvo interface is created in br-int and qbr linux bridge is created.

    Bridge br-int
        Controller "tcp:127.0.0.1:6633"
            is_connected: true
        fail_mode: secure
        Port br-int
            Interface br-int
                type: internal
        Port "tap339c7192-27"
            tag: 2
            Interface "tap339c7192-27"
                type: internal
        Port "qvo648e4034-c0"
            tag: 2
            Interface "qvo648e4034-c0"
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port int-br-ex
            Interface int-br-ex
                type: patch
                options: {peer=phy-br-ex}
    ovs_version: "2.6.1"

$ sudo brctl show
bridge name bridge id STP enabled interfaces
docker0 8000.0242b85e4d9c no
qbr648e4034-c0 8000.4e628aefd1dc no qvb648e4034-c0
       tap648e4034-c0

3. remove the service and check Neutron ports for the service removed well.
$ openstack port list
+--------------------------------------+------+-------------------+----------------------------------------------------------------------------+--------+
| ID | Name | MAC Address | Fixed IP Addresses | Status |
+--------------------------------------+------+-------------------+----------------------------------------------------------------------------+--------+
| 299a12ef-99dd-452a-bce8-e74a69ef0a24 | | fa:16:3e:47:39:35 | ip_address='192.168.0.6', subnet_id='70613cf3-7894-4096-af45-c2f9718ca2fb' | ACTIVE |
| 339c7192-270b-4724-92dd-cde87a4e1c59 | | fa:16:3e:7d:aa:27 | ip_address='192.168.0.2', subnet_id='70613cf3-7894-4096-af45-c2f9718ca2fb' | ACTIVE |
+--------------------------------------+------+-------------------+----------------------------------------------------------------------------+--------+

4. but the qvo and qbr still exist
    Bridge br-int
        Controller "tcp:127.0.0.1:6633"
            is_connected: true
        fail_mode: secure
        Port br-int
            Interface br-int
                type: internal
        Port "tap339c7192-27"
            tag: 2
            Interface "tap339c7192-27"
                type: internal
        Port "qvo648e4034-c0"
            tag: 4095
            Interface "qvo648e4034-c0"
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port int-br-ex
            Interface int-br-ex
                type: patch
                options: {peer=phy-br-ex}
    ovs_version: "2.6.1"

$ sudo brctl show
bridge name bridge id STP enabled interfaces
docker0 8000.0242b85e4d9c no
qbr648e4034-c0 8000.4e628aefd1dc no qvb648e4034-c0

Error logs from Kuryr plugin
2017-07-29 07:50:53.696 12 ERROR kuryr_libnetwork.utils [-] Unexpected error happened: The port doesn't exist for the name ee99c3fb74ea535e0041ba8694093fa1b93ec4fc685caab349172cdc5730c3a3-port: NoResourceException: The port doesn't exist for the name ee99c3fb74ea535e0041ba8694093fa1b93ec4fc685caab349172cdc5730c3a3-port