I love seeing these projects make use of the wide-open namespace/references that git provides (outside of the basic `refs/heads` for git branches and `refs/tags` for tags). It looks like they store the data in the `bugs` namespace [1] (so refs/bugs/foo).

Other projects also make use of alternate namespaces. The oft-forgotten built-in "git notes" puts stuff in the `refs/notes/` namespace (specifically in `refs/notes/commits`). Gerrit uses the virtual `refs/for/` namespace for receiving commits for review, stores project config in `refs/meta/config`, and stores User data in `refs/users/` in a special repo [2]. I'm sure others do interesting things.

Alternate uses of git's DAG model are fascinating.

[1] https://github.com/git-bug/git-bug/blob/bd936650ccf44ca33cf9...

[2] https://gerrit-review.googlesource.com/Documentation/config-...