Comment 2 for bug 1769912

Reviewed: https://review.openstack.org/567263
Committed: https://git.openstack.org/cgit/openstack/zun/commit/?id=e6eb3045c0e70f39ef4c8a84deb379d6abf7f72d
Submitter: Zuul
Branch: master

commit e6eb3045c0e70f39ef4c8a84deb379d6abf7f72d
Author: weikeyou <weikeyou@126.com>
Date: Wed May 9 23:35:54 2018 +0800

    Modify the rule of filtering glance tag

    In the current progress of filtering glance image tags,
    there are two problems:
    1 When use "repo:tag" to pull image , if the glance image
    tags were not updated , we will not get it even though the
    glance image is what we want.
    2 the current progress use update time to filter glance images,
    this is an unreliable parameters which with some randomness.

    we can use repo to find glance image firstly, if more than one
    image is returned, then use tag to filter.

    Change-Id: Ida4274688e7088e672c8963e75fd29ee524fbf97
    Closes-bug: #1769912