It was possible to create a volume and to do the following operations
with the volume; at the end, the volume itself is marked as ended, but
the volume is still available.
openstack volume create --size x foo
openstack volume snapshot create --volume <id> foo_snap
openstack volume create --snapshot <id_of_snap> clone
openstack volume delete --purge <id_of_foo>
openstack metric resource show <id_of_foo>
This commit fixes that issue.