When looking up storage volumes virsh uses multiple lookup steps. Some
of the steps don't require a pool name specified. This resulted into a
possibility that a volume would be part of a different pool than the
user specified:

Let's have a /var/lib/libvirt/images/test.qcow image in the 'default'
pool and a second pool 'emptypool':

Currently we'd return:
  $ virsh vol-info --pool emptypool /var/lib/libvirt/images/test.qcow
  Name:           test.qcow
  Type:           file
  Capacity:       100.00 MiB
  Allocation:     212.00 KiB

After the fix:
 $ tools/virsh vol-info --pool emptypool /var/lib/libvirt/images/test.qcow
 error: Requested volume '/var/lib/libvirt/images/test.qcow' is not in pool 'emptypool'

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1088667