Comment 10 for bug 1457527

The following patch will make sure that the BDM entry for a swap disk is created at all times (right now it would only be created if --swap was used iow if passed in as part of block_device_mapping_v2).

https://review.openstack.org/#/c/83516/

Most of the libvirt code knows how to handle both cases - but this is obviously not ideal. I will respin the patch and tag this bug - but we may need some code to handle instances booted befor the patch.