A couple of changes here:
* Ensure that the post-upgrade-hook runs BEFORE the config-changed to
set the openstack-origin/source back to distro. The former behaviour
breaks keystone quite badly.
* Ensure that the charm name is used, as discovered from the model, for
rabbitmq-server and percona-cluster to cope with different names for
the application in the model vs the charm name from the charm-store.
* Check whether the machine needs to be rebooted after the dist-upgrade
(before the do-release-upgrade), and reboot the machine first.
Otherwise, do-release-upgrade will fail.
66d95d65d7