Xen: VHD sequence validation needs to handle swap

[Rick Harris]

Swap in the image is going away since we generate it on the fly now.

Until it's removed however, we still need to account for it.

There is currently a bug in the VHD-sequence validation code where it will see 'swap.vhd' and expect another sequence number.

The fix is to skip 'swap.vhd'.

In the interest of sanity checking, other unrecognized VHDs will still raise an exception.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/10542

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/10542
Committed: http://github.com/openstack/nova/commit/40a84de65ae870c363587b3cacb1c1308eee069e
Submitter: Jenkins
Branch: master

commit 40a84de65ae870c363587b3cacb1c1308eee069e
Author: Rick Harris <email address hidden>
Date: Mon Jul 30 15:49:02 2012 +0000

    Xen: VHD sequence validation should handle swap.

    The VHD sequence validation code was erroneously counting `swap.vhd`,
    which caused it to raise an exception when a corresponding numbered VHD
    was not found.

    The fix is to simply ignore the `swap.vhd` file.

    Other unknown VHDs will generate an exception, but from a
    sanity-checking perspective, this is a Good Thing(tm).

    Fixes bug 1030939

    Change-Id: Ic82ae27a4af7ea8f7669fd006aea1a310b691218