Comment 5 for bug 1680616

Reviewed: https://review.openstack.org/511682
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=e2c2b1d586f4e24f0e4f3fc760c687e03c501ec7
Submitter: Zuul
Branch: stable/ocata

commit e2c2b1d586f4e24f0e4f3fc760c687e03c501ec7
Author: Matt Riedemann <email address hidden>
Date: Thu Apr 6 17:59:34 2017 -0400

    Fix joins in instance_get_all_by_host

    Some callers of instance_get_all_by_host are passing
    in columns_to_join=[], like the _sync_scheduler_instance_info
    periodic task in the compute manager, to avoid unnecessary
    joins with other tables.

    The problem was columns_to_join wasn't being passed through
    to _instance_get_all_query which builds the actual query
    method, and defaults to join on info_cache and security_groups.

    This fixes the problem by passing through columns_to_join and
    provides tests to show it working both with and without the joins.

    Change-Id: I69f2ddca8fb0935e03b0f426891d01360940a85a
    Closes-Bug: #1680616
    (cherry picked from commit d52bcc616f2d1c0df7bad8a6f5a00adc7ad1fb27)