We don't need to log a warning when we can't delete an allocation for an instance that doesn't exist

[Matt Riedemann]

These are all over the n-cpu logs in master branch CI runs now:

http://logs.openstack.org/75/405575/6/check/gate-tempest-dsvm-neutron-full-ubuntu-xenial/e1c5575/logs/screen-n-cpu.txt.gz?level=TRACE#_2016-12-22_16_52_19_551

2016-12-22 16:52:19.551 7348 WARNING nova.scheduler.client.report [req-8eeeb512-bfe6-4f23-a9b1-92eff8b55fb3 tempest-DeleteServersTestJSON-565294557 tempest-DeleteServersTestJSON-565294557] Unable to delete allocation for instance 19d35113-6c72-42ca-8b73-b76f630bb211: (404 404 Not Found

The resource could not be found.

 No allocations for consumer '19d35113-6c72-42ca-8b73-b76f630bb211' )

--

If we're trying to delete something that doesn't exist, we don't need to treat it as a warning or something that the operator needs to investigate.

Based on the name of the tenant, these are probably from tests where the instance is deleted while it's building.

This also shows up a ton in gate runs:

http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22Unable%20to%20delete%20allocation%20for%20instance%5C%22%20AND%20message%3A%5C%22404%20404%20Not%20Found%5C%22%20AND%20tags%3A%5C%22screen-n-cpu.txt%5C%22&from=7d

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/414349

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/414349
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=8ea3c838d8637b602f5d1d8d3f3279579c3994c8
Submitter: Jenkins
Branch: master

commit 8ea3c838d8637b602f5d1d8d3f3279579c3994c8
Author: Matt Riedemann <email address hidden>
Date: Thu Dec 22 18:03:32 2016 -0500

    Ignore 404s when deleting allocation records

    We don't need to emit a warning when trying to delete
    an allocation record that doesn't exist. We see these
    warnings all over the CI runs because of Tempest tests
    that delete a server while it's building, in which case
    the allocation record may have never been created.

    Change-Id: I472fe1a091dc2524c50873d4fd916bcc535f51c7
    Closes-Bug: #1652155

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 15.0.0.0b3 development milestone.