libvirt/hyperv do not support Glance

[Thierry Carrez]

libvirt and hyperv are not compatible with Glance, they unconditionally use nova-objectstore.

libvirt and hyper-V use nova.virt.images to fetch images, which supports only s3 or local filesystem (through the use_s3 flag).
xenapi on the other hand implemented a switch (based on xenapi_image_service flag, should probably use image_service instead) to support Glance or the objectstore.

Some refactoring is needed so that the switch is implemented at nova.virt.images level.

[Thierry Carrez (ttx)]

See naive fix in attached branch. Rather than refactoring which would carry regression risks, it just handles the case where --image_service=nova.image.glance.GlanceImageService. I can boot a VM alright with this patch.

[Thierry Carrez (ttx)]

Or maybe we should just consider it an unsupported case in Bexar and properly fix it in Cactus.