Comment 2 for bug 1644697

Reviewed: https://review.openstack.org/402291
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=a909ed26c2aa6daf2c5fc59a2f575a66cdddbfb5
Submitter: Jenkins
Branch: master

commit a909ed26c2aa6daf2c5fc59a2f575a66cdddbfb5
Author: Tony Breeds <email address hidden>
Date: Fri Nov 25 15:48:35 2016 +1100

    Add constraints support to run_tests.sh

    Currently developers need to manually build a constratined venv if they
    want to match the versions that are tested in the gate. This change
    adds logic to run_tests.sh and install_venv*.py to default to the same
    constraints file used in the gate.

    With constraints enabled the 'churn' in the environment should be
    minimised so remove the developer optimisation for detecting when
    packaged versions change and always just install/update. This has the
    down side of making the script preamble slightly longer but we always
    print_help() so I don't think it'll be terribly inconvenient.

    Change-Id: I9bf85adb5aa2c85d8c0f0f22ac9efe5cac3646c0
    Closes-Bug: 1644697