Test volume list caching
Test volume list caching

This behavior actually causes problems, but we want to make sure it is
covered before changing behaviors.

Change-Id: I5c7558a4b036d6b177bb01e8fb0582d936528c61

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