hostname not set on network reset call

[Christopher Lefelhocz]

The hostname has been removed from xenstore after spawn has completed, so that windows instances do not get renamed on very reboot.

We should look at setting the hostname for the duration of the reset networking call.

This affects xen solutions in particular that use the agent form of communication.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/50373

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/51308

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/51308
Committed: http://github.com/openstack/nova/commit/34470cf13dbe4ec20d413989ea40ffe97a7df1cf
Submitter: Jenkins
Branch: master

commit 34470cf13dbe4ec20d413989ea40ffe97a7df1cf
Author: Christopher Lefelhocz <email address hidden>
Date: Fri Oct 11 03:22:03 2013 +0000

    Xenapi: set hostname when performing a network reset

    The hostname is removed from the metadata on Xen to address an
    issue where windows instances get renamed on reboot. This
    becomes a problem when a network reset is called for instances
    using the agent communication mechanism. In that case the
    agent will incorrectly rename the host. Thus the
    hostname needs to be set prior and cleared after a network reset.

    The setting of the metadata params also need to be atomic so
    locking was added that matches to the locking provided by
    other data (network metadata).

    Fixes bug 1236877

    Change-Id: I473870994c826f85a7c6ec1448171c4e4ee40ff0