xenapi: agent errors should be reported but not block the build

[John Garbutt]

In havana, if a VM is expected to have the agent installed, we fail hard on errors calling the agent.

Really we should only ensure errors are reported, and not block the build, as its possible (with DHCP, etc) that the VM will still work fine.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/49156

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/49156
Committed: http://github.com/openstack/nova/commit/604ec1c5786256a8e9390bbe0414df799370862b
Submitter: Jenkins
Branch: master

commit 604ec1c5786256a8e9390bbe0414df799370862b
Author: John Garbutt <email address hidden>
Date: Tue Oct 1 10:53:37 2013 +0100

    xenapi: stop agent errors stopping build

    We should still report agent errors, but they should not stop a server
    from building, because that server still may be ready to use.

    Once this change is in place, we can look to selectively add back in
    certain errors that fail the build, as we decide what makes sense on a
    case by case basis.

    Fixes bug 1233548
    Change-Id: I32b9e8dbc6e28a045ac8ef159afe1cf74b7ac6fb