Updated openstack/openstack
Project: openstack-dev/devstack  b0511b504b90908fd76fbcddc1edbf1c75c7e8ca
null
Use the $SERVICE_HOST in backup_swift_url

The $SERVICE_HOST is used to specify the swift proxy endpoint,
the c-bak should use the same endpoint.

Change-Id: Ia815f514839b0d1ec3fb9bb40992637c4f123e06