Invalidate volume cache when waiting for attach
Invalidate volume cache when waiting for attach

We need to invalidate the volume cache when waiting for volume attach to
complete otherwise we never see the attachment complete (the cached data
is perpetually stale).

Change-Id: If875997b7fb6682ef4752852c58ea1b4cf52de91

openstack/python-openstacksdk,dtroyer/python-openstacksdk,openstack-infra/shade,openstack/python-openstacksdk,dtroyer/python-openstacksdk,openstack-infra/shade,stackforge/python-openstacksdk,stackforge/python-openstacksdk