libvirt: spawning an instance may have an additional 4 db writes

[Gary Kotton]

instance save is used by the driver when it does not need to be. each instance save will invoke a db access. after the spawn method is called the instance is updated so there is no need for the save

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/119622

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/119622
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=bc40e85c0278afcca74892fc818da1e005f13fc7
Submitter: Jenkins
Branch: master

commit bc40e85c0278afcca74892fc818da1e005f13fc7
Author: Gary Kotton <email address hidden>
Date: Sun Sep 7 07:25:31 2014 -0700

    libvirt: Unnecessary instance.save(s) called

    When spawning an instance there may a considerable amount of
    instance.save() called. This is not necessary as the compute
    manager will update the instance after the spawn method has
    successfully completed.

    Change-Id: I61610b3869caeb7822eab3f2d09335744b75db28
    Closes-bug: #1366548