400 error responses with no body are difficult to debug

[Russell Sim]

currenty if the response has no error body all that will be returned from the request is a error that looks like

Details: {u'badRequest': {u'message': u'Invalid input received: Bad request', u'code': 400}}

This will probably only occur in 2 cases: Header Line Too Long and Headers Too Large. They ar responses returned from eventlet and can't be returned with a JSON body.

It would be much easier to debug these problem if the HTTP reason code is encoded in the message instead of being thrown away.

e.g.

Details: {u'badRequest': {u'message': u'Invalid input received: Header Line Too Long', u'code': 400}}

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/55478

[Openstack Gerrit (openstack-gerrit)]

Reviewed: https://review.openstack.org/55478
Committed: https://git.openstack.org/cgit/openstack/python-cinderclient/commit/?id=52ce0b205e336d7545947a13b4a4f3dfc490d51e
Submitter: Jenkins
Branch: master

commit 52ce0b205e336d7545947a13b4a4f3dfc490d51e
Author: Russell Sim <email address hidden>
Date: Thu Nov 7 11:28:05 2013 +1100

    When there is no error body return the HTTP reason

    Return the response reason when there is no message body to return.

    DocImpact
    Change-Id: Ia60da4f04b059a13fcbe0059bb42fd77f272d8aa
    Closes-Bug: 1248773