Extract the volume ID from Glance multistore URLs.

[Peter Penchev]

If Glance's Cinder client is used as part of a multistore Glance installation, then Glance will store the URLs for the location of the Cinder volumes not as `cinder://uuid`, but as `cinder://backend_group/uuid`, see e.g. https://github.com/openstack/glance_store/blob/master/glance_store/_drivers/cinder.py#L443

This means thackt when Cinder tries to parse this URL to extract the volume ID when creating a volume from a Cinder-backed Glance image, it will take more than just the volume's UUID - it will also grab the "backend_group/" portion, leading to a failure to look up the volume immediately afterwards; see https://github.com/openstack/cinder/blob/master/cinder/volume/flows/manager/create_volume.py#L679

The fix is to only use the last /-terminated portion of the URL as the volume UUID. I will submit a Cinder change for review immediately.

Thanks for your time and consideration, and keep up the great work!

[Peter Penchev (openstack-dev-s)]

Right, so I messed up the Closes/Closes-Bug commit message lines, but see https://review.opendev.org/c/openstack/cinder/+/803862

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Peter Penchev <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/cinder/+/803862
Reason: There is a better approach in https://review.opendev.org/c/openstack/cinder/+/755654 although it needs a bit more work (I'll see what I can do about it there).