Comment 9 for bug 1808063

Reviewed: https://review.openstack.org/625086
Committed: https://git.openstack.org/cgit/openstack/glance/commit/?id=044d6b45f98238f4a5745922ef93223d05771d4c
Submitter: Zuul
Branch: master

commit 044d6b45f98238f4a5745922ef93223d05771d4c
Author: Chris Dent <email address hidden>
Date: Thu Dec 13 18:59:39 2018 +0000

    Guard __getattr__ on QuotaImageTagsProxy

    In the related bug (below) we can see getting tags from a
    QuotaImageTagsProxy can sometimes cause an infinite loop, presumably
    because of bizarre threading circumstances. To at least provide a bit
    more information when this bizarre circumstance happens, instead
    of looping, resulting in a stackoverflow and the processing being
    terminated without a traceback, now raise a TypeError. This should
    help figure out what may be going on in the rare times this happens.

    Also, it is generally a healthy idea to always have a guard like this
    in a __getattr__ that uses an attr.

    Change-Id: Ib4ad119a838d5b06372d9302dc6608da1772eed6
    Related-Bug: #1808063