Comment 11 for bug 2003993

Reviewed: https://review.opendev.org/c/openstack/devstack/+/871943
Committed: https://opendev.org/openstack/devstack/commit/30a7d790b6bf45bbcc6333008621b093c84055d1
Submitter: "Zuul (22348)"
Branch: stable/zed

commit 30a7d790b6bf45bbcc6333008621b093c84055d1
Author: Ghanshyam Mann <email address hidden>
Date: Thu Jan 26 22:28:07 2023 -0600

    Fix setting the tempest virtual env constraints env var

    Devstack set the env var TOX_CONSTRAINTS_FILE/UPPER_CONSTRAINTS_FILE
    which are used to use the constraints during Tempest virtual env installation.
    Those env var are set to non-master constraint when we need to use non-master
    constraints but when we need to use the master constraints we do not set/reset
    them point to master constraints. This create the issue when running the grenade
    job where we run Tempest on the old devstack as well as in the new devstack.
    When tempest is installed on old devstack then old tempest is used and it sets
    these env var to stable/<branch> constraints (this is the case when old devstack
    (the stable branch is in EM phase) uses the old tempest not the master tempest),
    all good till now. But the problem comes when in the same grenade script run
    upgrade-tempest install the master tempest (when new devstack branches are in
    the 'supported' phase and use the master tempest means) and are supposed to use
    the master constraints. But the TOX_CONSTRAINTS_FILE/UPPER_CONSTRAINTS_FILE env
    var set by old tempest is used by the tempest and due to a mismatch in constraints
    it fails.

    This happened when we tried to pin the stable/wallaby with Tempest 29.0.0
    - https://review.opendev.org/c/openstack/devstack/+/871782

    and table/xena grenade job failed (stable/xena use master tempest and supposed
    to use master constraints)
    - https://zuul.opendev.org/t/openstack/build/fb7b2a8b562c42bab4c741819f5e9732/log/controller/logs/grenade.sh_log.txt#16641

    We should set/reset those constraint env var to master constraints if configuration
    tell devstack to use the master constraints.

    [1] https://github.com/openstack/devstack/blob/71c3c40c269a50303247855319d1d3a5d30f6773/lib/tempest#L124

    Closes-Bug: #2003993
    Change-Id: I5e938139b47f443a4c358415d0d4dcf6549cd085
    (cherry picked from commit 7fe998109bda8cdd5cb5ba4a0e02c6c83cb0566d)