$ git clone -n https://src.fedoraproject.org/rpms/rust-timebomb.git /var/lib/mock/f41-build-side-1-3134954-39764/root/chroot_tmpdir/scmroot/rust-timebomb
Cloning into '/var/lib/mock/f41-build-side-1-3134954-39764/root/chroot_tmpdir/scmroot/rust-timebomb'...
$ git fetch origin 62f3e94cd679e9a0a500978a34bc1372acddfd33:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-timebomb
 * [new ref]         62f3e94cd679e9a0a500978a34bc1372acddfd33 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62f3e94 unused leaf package for more than two release cycles