Comment 4 for bug 1185190

Reviewed: https://review.openstack.org/30954
Committed: http://github.com/openstack/nova/commit/04d9fb406783ba5934d9cb249550a92202555bc7
Submitter: Jenkins
Branch: milestone-proposed

commit 04d9fb406783ba5934d9cb249550a92202555bc7
Author: Chris Behrens <email address hidden>
Date: Wed May 29 14:21:00 2013 +0000

    Don't delete sys_meta on instance delete

    Unfortunately, we require to access instance_system_metadata to get
    data (specifically at least instance_type data) for instances that have
    been deleted.

    There's 2 cases where this is true:

    1) nova-api supports showing deleting instances when you specify a
    'changes-since' param.
    2) The _usage_audit_log periodic task pulls all instances during the
    audit period, which includes instances that have been deleted during
    that period.

    This reverts commit 17bca438954638d74035d560e826a26a532b3ea3, which was
    attempting to fix a bug where we leave instance_system_metadata entries
    undeleted from the DB. There's not an easy way to query for the deleted
    sys_meta data in an efficient manner, and leaving the entries undeleted is
    the lesser of the 2 evils for now.

    Fixes bug 1185190

    Change-Id: I898f0546c49126dcc56a4237120082f95dc82304
    (cherry picked from commit 4885aa28706a1858f4fc51a0d2c661eec05139c0)