Comment 18 for bug 1744160

Reviewed: https://review.openstack.org/538036
Committed: https://git.openstack.org/cgit/openstack/oslo.versionedobjects/commit/?id=c95f0c876840e36f37acb14d5eec5238d85e7dce
Submitter: Zuul
Branch: stable/queens

commit c95f0c876840e36f37acb14d5eec5238d85e7dce
Author: Sean McGinnis <email address hidden>
Date: Thu Jan 18 16:52:03 2018 -0600

    Handle TZ change in iso8601 >=0.1.12

    The iso8601 lib introduced a change such that if running on python
    3.2 or later it internally uses the python timezone information
    instead of its own implementation. This does not change direct
    date handling, but when converting this value there is a slight
    difference where now python 2.x will show UTC times as "UTC", but
    on python 3 they will end up with "UTC+00:00".

    The to_primitive call for DateTime fields was doing an exact match
    on "UTC" to determine whether to include "Z" in the resulting string.
    This updates that handling to recognize either of the new values.

    Change-Id: Iff2e5a5b056605fae59f2489cc7baa1fc2e3352f
    Closes-bug: #1744160
    (cherry picked from commit 9c4aefb8ea88fd5505602c95f4762fdeb3aea183)
    Signed-off-by: Matthew Thode <email address hidden>