Updated openstack/openstack
Project: openstack/nova  1ab85c704ecbef9fa9e0e2aed6024a6e15565fff

virt: use instance object for attach in block_device

It will be better if we'll use `instance` like object.

Change-Id: I56b3931da7339d2d350a7d1368dd39c7e398d3e6