Stopped unit agents show up as "unit agent lost"

[John A Meinel]

If you actively stop a unit agent, that agent just shows up as 'lost' in the `juju status` UX:

juju ssh 8 ; juju_stop_unit ubuntu-lite/5

juju status
...
ubuntu-lite/5* unknown lost 8 10.5.24.191 agent lost, see 'juju show-status-log ubuntu-lite/5'

However, we do have a machine agent there, it knows that it is explicitly stopping that agent, so we could inform the controller that we have explicitly stopped that unit. And the help text could point users towards `juju_start_unit`, or some other pieces of the introspection runtime. (Maybe it should also explicitly have an entry in 'juju show-status-log'.)

[Canonical Juju QA Bot (juju-qa-bot)]

This Medium-priority bug has not been updated in 60 days, so we're marking it Low importance. If you believe this is incorrect, please update the importance.