Model upgrade from 2.9.22 to 2.9.27 machine service's aren't always properly restarted

[Chris Johnston]

After deploying an environemnt with 2.8.8 I upgraded the controller and models to 2.9.22, and then the controller to 2.9.27. Then upgrading the model from 2.9.22 to 2.9.27 some of the machine agent services are unable to restart. This appears to be due to something getting stuck while trying to stop the service. When looking into this further, it was determined that the two things that the service was waiting to stop were actually stopped.

[Heather Lanigan (hmlanigan)]

From the engine report, the migration-fortress didn't move to stopped.
error: 'must restart: an agent upgrade is available'
  migration-fortress:
    inputs:
    - upgrade-steps-flag
    - upgrade-check-flag
    start-count: 1
    started: "2022-03-30 17:25:44"
    state: stopping
  migration-inactive-flag:
    error: connection is shut down
    inputs:
    - api-caller
    start-count: 2
    state: stopped
  migration-minion:
    error: connection is shut down

    - central-hub
    - http-server-args
    - is-controller-flag
    state: stopped

[Heather Lanigan (hmlanigan)]

The machine agent can be restarted with `systemctl restart jujud-*` to resolve the issue.