Comment 4 for bug 1884587

Reviewed: https://review.opendev.org/738737
Committed: https://git.openstack.org/cgit/openstack/glance/commit/?id=fcba03989feed85a3301e53b252f766eabeeba3c
Submitter: Zuul
Branch: stable/ussuri

commit fcba03989feed85a3301e53b252f766eabeeba3c
Author: Dan Smith <email address hidden>
Date: Tue Jun 23 07:12:12 2020 -0700

    Check authorization before import for image

    Right now we only check to see if the user can see the image before
    we kick off an import operation. However, that will never work unless
    the user is the *owner* of the image (or an admin) which means we
    return a 202 to the API caller and then the task fails immediately.

    This change makes us check that authorization up front and return an
    appropriate error to the user so they know it failed, and avoid
    starting a task destined for failure.

    Note that there was already a check for a Forbidden result when calling
    the import API. However, that used a context.owner=None which could never
    happen in reality. A more suitable check would have been to use a context
    with a different real owner, but it turns out that the task creation
    would have succeeded in that case as well. This test is changed to use
    an alternate owner and ensure that we get the forbidden result from the
    new check immediately.

    Change-Id: I385f222c5e3b46978b40bdefdc28fcb20d9c67d3
    Closes-Bug: #1884587
    (cherry picked from commit c930638fcf58b43d53903cfc30e06fd6919bdad6)