I configured a git2 user, with login shell set to git-shell and home to /srv/git2. It should only provide access to git-pull and git-push on git2@parabolagnulinux.org. I also mirrored abslibre.git and abslibre-mips64el.git on it.

It works ok but we have to change the path to the absolute path of the repo, for instance:

ssh://gparabola/abslibre.git => ssh://gparabola/srv/git2/abslibre.git

There's not much documentation out there, but I think we can put a path convertor on the authorized_keys command option (add /srv/git2/ to /repo.git)

Done! pubkeys must be put on hackers.git now