Update the Image

% curl -i -X PATCH -H "X-Auth-Token: $OS_AUTH_TOKEN" \
       -H "Content-Type: application/openstack-images-v2.1-json-patch"
       -d '[{"op": "add", "path": "/login-user", "value": "root"}]' \
       $OS_IMAGE_URL/v2/images/7b97f37c-899d-44e8-aaa0-543edbc4eaad

HTTP/1.1 200 OK
Content-Length: 477
Content-Type: application/json; charset=UTF-8
Date: Fri, 15 Nov 2013 00:46:50 GMT

{
    "id": "7b97f37c-899d-44e8-aaa0-543edbc4eaad",
    "name": "Ubuntu 12.10",
    "status": "queued",
    "visibility": "private",
    "protected": false,
    "tags": ["ubuntu", "12.10", "quantal"],
    "login_user": "root",
    "created_at": "2013-11-15T00:46:48Z",
    "updated_at": "2013-11-15T00:46:50Z",
    "file": "/v2/images/7b97f37c-899d-44e8-aaa0-543edbc4eaad/file",
    "self": "/v2/images/7b97f37c-899d-44e8-aaa0-543edbc4eaad",
    "schema": "/v2/schemas/image"
}