xenapi: BittorrentStore tries to load entry points that don't exist in tree

[Matt Riedemann]

http://git.openstack.org/cgit/openstack/nova/tree/nova/virt/xenapi/image/bittorrent.py#n75

There are no entry points in nova's setup.cfg for this:

        matches = [ep for ep in
                   pkg_resources.iter_entry_points('nova.virt.xenapi.vm_utils')
                   if ep.name == 'torrent_url']

For anyone using torrents with the xenapi driver, they should set the config option CONF.xenserver.torrent_base_url.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/182048