A regression was introduced in
I970c10f9b50092b659fa2d88bd6a02f6c69899f2
on backends supporting storage pools. By extracting the
'host@backend' out of the host attr from a parent volume,
the scheduler may attempt to put volumes into other pools
belonging to the backend.
Many backends cannot clone across storage pools,
or create storage volumes from snapshots from other
storage pools.
Change-Id: Ic4c8f29bef2c82550d6d6f03f8fa1dc80696f56e
Closes-Bug: #1732557
39816f9ff3