SAWarning using empty IN on assignment.actor_id

[Clint Byrum]

Dec 18 02:51:28 ci-overcloud-controller0-nvacfowhjcy2 keystone: /opt/stack/venvs/openstack/local/lib/python2.7/site-packages/sqlalchemy/sql/default_comparator.py:35: SAWarning: The IN-predicate on "assignment.actor_id" was invoked with an empty sequence. This results in a contradiction, which nonetheless can be expensive to evaluate. Consider alternative strategies for improved performance.

This should be fairly straight forward to address.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/143175

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/143175
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=600c236e2111a770e478040a8a78bb62ef27ac39
Submitter: Jenkins
Branch: master

commit 600c236e2111a770e478040a8a78bb62ef27ac39
Author: Brant Knudson <email address hidden>
Date: Fri Dec 19 14:11:00 2014 -0600

    Fix to not use empty IN clause

    When an empty IN clause is used with sqlalchemy, a warning is
    printed:

     SAWarning: The IN-predicate on "assignment.actor_id" was invoked
     with an empty sequence. ...

    With this fix, these warnings should no longer be printed.

    The tests are changed to convert these warnings into errors.

    Change-Id: I58c7e5f11fdac9bbc1e9a970ce690ea113e2bd95
    Closes-Bug: #1404354