Replace locations with multi-requests returns wrong result

[wangxiyuan]

Env: glance-master,

Reproduce:
1. Suppose there is an image with its location in Glance already.

2. send a location-update request with two bodies, like:

[
    {
      "op":"replace",
   "path":"/locations",
      "value":[
      ]
   },

   {
      "op":"replace",
   "path":"/locations",
      "value":[
        {
            "url": "swift+http://admin:admin:root@10.229.45.145:35357/v3/glance/wrong-test.img",
             #note: this is a wrong location url.
            "metadata": {}
        }
      ]
   }
]

The first body is to set the location to empty. The second body is to set the location to a new one, but the url is wrong.

3. the Glance raise an error: Invalid locations. Because that I send a wrong url to Glance.

4. Show the image.

Expect result:
the image's status is 'queued' and the location is empty.

Actual result:
the image's status is 'active', but the location is empty.

The reason is that Glance save the image' information to db when the hole request is over. But i give the wrong url, so that the the location has been removed and image didn't be saved to db.

So IMO, we should take db saving each time we change the location.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/261927

[OpenStack Infra (hudson-openstack)]

Change abandoned by wangxiyuan (<email address hidden>) on branch: master
Review: https://review.openstack.org/261927