For a variety of reasons (especially the fact many current commands don't update the site metadata properly), the site metadata and the repo states can get out of sync (e.g. if a repo is deleted). There should be an explicit clean command that updates the metadata to remove any deleted repos/mirrors, as well as as adding any new mirrors or raw trees that are currently missing from the metadata.
Marking all remaining PulpDist issues as CLOSED-EOL It doesn't make sense to leave these issues open, as PulpDist hasn't been in active development for quite some time, and restarting development would involve a significant modernisation effort that would likely render many of these requests irrelevant.