Comment 2 for bug 1993319

I have a stepping stone pr up to handle the general case of `juju refresh` upgrading resources where there is no new charm available:

https://github.com/juju/juju/pull/15196

Next step is to ensure that ori-images are properly upgraded.

This change is unrelated to charmhub. It's not clear based on the code I found that this functionality worked with charmstore either. One of the problems resolved was due to code in state which didn't resolve pending resources unless the charm revision changed too. Nor was the CharmModifiedVersion updated to trigger the upgrade charm hook. There were more.