"github-backup [...] backs up everything GitHub publishes about the repository, including branches, tags, other forks, issues, comments, wikis, milestones, pull requests, watchers, and stars."
Cool. Along with those looking to migrate, it's good for the good ol' paranoid people.
Can you put the data back again, though? Last I saw it wasn't possible to use the API to, e.g., add issues owned by someone else. (I was wanting to migrate mailing list archives off SourceForge.)
Perfect! I have been searching fruitlessly for exactly this since GitHub changed and went insane.