$ git clone -n https://src.fedoraproject.org/rpms/rust-firestorm.git /var/lib/mock/f41-build-side-1-2954323-35544/root/chroot_tmpdir/scmroot/rust-firestorm
Cloning into '/var/lib/mock/f41-build-side-1-2954323-35544/root/chroot_tmpdir/scmroot/rust-firestorm'...
$ git fetch origin 8873f3be3478e0747b83b4bde35ff82709435772:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-firestorm
 * [new ref]         8873f3be3478e0747b83b4bde35ff82709435772 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8873f3b unused leaf package for more than two release cycles