Stub out Torrent URL lookup fn in tests

[Rick Harris]

Torrent URL lookup functions are registered via entry-points.

If the tests run in an environment where the production lookup function is present, it will use that; not what we want for tests.

Instead, we should stubout entry-points so we have a mock URL lookup function.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/41465

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/41465
Committed: http://github.com/openstack/nova/commit/feb747523df20d6471b77fa120ef19133ea20bfc
Submitter: Jenkins
Branch: master

commit feb747523df20d6471b77fa120ef19133ea20bfc
Author: Brian Elliott <email address hidden>
Date: Mon Jul 29 23:49:33 2013 +0000

    Stub out entry points in LookupTorrentURLTestCase

    Torrent URL lookup functions are registered via entry-points.

    If the tests run in an environment where the production lookup function is
    present, it will use that; not what we want for tests.

    Instead, we should stubout entry-points so we have a mock URL lookup function.

    Fixes bug 1211396

    Change-Id: Ibc2b34bfdcecaad4c53fb00e925a8b21965d8577