Toggling the "release" setting doesn't seem to work

[barryprice]

Jenkins and plugins versions report

Not relevant

What Operating System are you using (both controller, and any agents involved in the problem)?

Ubuntu 18.04, Juju 2.8.9

Reproduction steps

Deploy the charm with "release" set to bundle.

Allow installation to continue.

Set "release" to e.g. "lts".

Expected Results

I would expect the charm to set up an apt source for the upstream LTS Jenkins, and install/upgrade Jenkins from that source.

Actual Results

Nothing appears to happen.

Anything else?

The simplest workaround seems to be to add-unit after changing the setting, then removing the original unit.