Return 200 when execute router-list-on-l3-agent api with incorrect agent_id

[Hirofumi Ichihara]

Neutron server return HTML code 200 when users execute router-list-on-l3-agent with incorrect agent_id.
Users expect to return HTML code 404.

$ neutron agent-list
+--------------------------------------+--------------------+--------------------------------------+-------+----------------+---------------------------+
| id | agent_type | host | alive | admin_state_up | binary |
+--------------------------------------+--------------------+--------------------------------------+-------+----------------+---------------------------+
| 21b32f05-df03-4ecf-a0cb-b5e4d6a83397 | DHCP agent | vagrant-ubuntu-trusty-64.localdomain | :-) | True | neutron-dhcp-agent |
| 5d1cc93d-026d-41f7-8608-e9b14e254036 | Open vSwitch agent | vagrant-ubuntu-trusty-64.localdomain | :-) | True | neutron-openvswitch-agent |
| 88cb8c8e-43c4-47da-9453-be1908328cd6 | L3 agent | vagrant-ubuntu-trusty-64.localdomain | :-) | True | neutron-l3-agent |
| f6eb352e-d374-4f98-86ed-e7571787336c | Metadata agent | vagrant-ubuntu-trusty-64.localdomain | :-) | True | neutron-metadata-agent |
+--------------------------------------+--------------------+--------------------------------------+-------+----------------+---------------------------+

I executed API with "hoge" as incorrect agent_id.
$ curl -i -X GET http://192.168.0.4:9696/v2.0/agents/hoge/l3-routers.json -H "Accept: application/json" -H "X-Auth-Token: 6b243da4b7414a65b12567df817f6f6c"
HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Content-Length: 15
X-Openstack-Request-Id: req-8a12b884-e5dd-4f50-ba21-b4823861e915
Date: Thu, 22 Jan 2015 08:01:39 GMT

{"routers": []}

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/149531

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/149531
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=8dde08679902149576a9173ebda3f847e65c964f
Submitter: Jenkins
Branch: master

commit 8dde08679902149576a9173ebda3f847e65c964f
Author: Hirofumi Ichihara <email address hidden>
Date: Fri Jan 23 17:30:53 2015 +0900

    Return 404 when executing router-list-on-l3-agent with invalid agent_id

    Neutron server returns HTML code 200 when users execute
    router-list-on-l3-agent with invalid agent_id.
    Users expect HTML code 404 to be returned.

    Change-Id: Ifadca8d6573a94abc3580a0de4463b755ef12a24
    Closes-bug: 1413500