Mark Repo as "archived" or "inactive" (BB-720)

I've got a couple repositories that I only keep up for archival reasons. It's actually slightly irritating (then again, I'm the type to garbage-collect forks often, so maybe I'm weird). It'd be really great if there was a way to indicate that a project was inactive (and maybe disallow all pushing to inactive-flagged repos?) so it wouldn't show in the quick-access repo dropdown list.