Comment 9 for bug 1874535

Reviewed: https://review.opendev.org/723529
Committed: https://git.openstack.org/cgit/openstack/validations-common/commit/?id=07d9c9621ef28b492ca093cdd110bfe951ede90d
Submitter: Zuul
Branch: master

commit 07d9c9621ef28b492ca093cdd110bfe951ede90d
Author: danpawlik <email address hidden>
Date: Mon Apr 27 15:16:57 2020 +0200

    Move unit tests execution to stestr

    From time to time, unit tests execution fails with error:
    "TypeError: 'NoneType' object is not iterable". It seems that
    problem is in unittest2 library, which is used by testtools for
    executing the tests.
    Stestr lib is usinig unittest by default and the problem does not appear
    for several hundred launches.

    Change-Id: Ic1053353a87ebd44f20c607651772928020b9e66
    Closes-Bug: #1874535