xenapi: Do not retry snapshot uploads on glance 500

[Brian Elliott]

If Glance returns a 500 response on an initial attempt to upload
a snapshot image, it will set the image status to KILLED/DELETED.
Any retry attempts will fail with a 409 response.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/110349

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/110349
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=77aea0e6a3d77f3c747a3f0d7126a8fbfae94263
Submitter: Jenkins
Branch: master

commit 77aea0e6a3d77f3c747a3f0d7126a8fbfae94263
Author: Brian Elliott <email address hidden>
Date: Tue Jun 10 16:46:15 2014 +0000

    xenapi: Do not retry snapshot upload on 500

    If Glance returns a 500 response on an initial attempt to upload
    a snapshot image, it will set the image status to killed. Any retry
    attempts will fail with a 409 response.

    Hence, Nova should not attempt to retry the upload in this case, which
    will eliminate many pointless retries.

    Closes-Bug: 1349933

    Change-Id: I1a8f2416923a368b02cf8963c747ebbb24d749a1