Description of change
Wire up the CAAS operator so it informs each of its uniter workers when a charm upgrade is available. The uniters will run the upgrade-charm hook. The operator will first have reacted to the charm upgrade by downloading and unpacking the charm.
Also a drive by fix for an intermittent caas operator test failure.
QA steps
Deploy and upgrade a charm on both caas and iaas models.
Bug reference
https://bugs.launchpad.net/bugs/1758828
该提问来源于开源项目：juju/juju
