removeFloatingIp action should return 400 rather than 404 when remove an removed floating ip

[wangpan]

If we remove a floating ip which is not associated with an instance, the response is like this:
HTTP/1.1 404 Not Found
and the body is None.
expected is like this:
HTTP/1.1 400 Bad Request
with body {"badRequest": {"message": "Floating ip 172.0.0.1 is not associated with an instance.", "code": 400}}

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/22283

[wangpan (hzwangpan)]

As the suggestion of Mauro S. M. Rodrigues, HTTPUnprocessableEntity is the better response instead of HTTPBadRequest.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/22283
Committed: http://github.com/openstack/nova/commit/5b38c5c6fe57f7b0d3e36a5d0206488fa01106c0
Submitter: Jenkins
Branch: master

commit 5b38c5c6fe57f7b0d3e36a5d0206488fa01106c0
Author: Wangpan <email address hidden>
Date: Tue Feb 19 13:14:06 2013 +0800

    Return proper error messages while disassociating floating IP

    Currently, when a floating IP is not associated with an instance, and if we try
    to disassociate it, a response likes "HTTP/1.1 404 Not Found" will be returned,
    it is not proper, so change it to "HTTP/1.1 422 Unprocessable Entity" with body
    likes '{"computeFault": {"message": "Floating ip 172.24.4.225 is not associated
    with instance a33857af-b18b-4b88-a5cc-7d84c7fd41c8.", "code": 422}}'.

    Fixes bug: #1129719

    Change-Id: I18194ccf59edb5eb2bcd52a65f38d5632fef95d3