$ git clone -n https://src.fedoraproject.org/rpms/firecracker.git /var/lib/mock/f40-build-1915211-25086/root/chroot_tmpdir/scmroot/firecracker
Cloning into '/var/lib/mock/f40-build-1915211-25086/root/chroot_tmpdir/scmroot/firecracker'...
$ git fetch origin 55a65000f957dea65e0ab4b2f80578c7eec20251:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/firecracker
 * [new ref]         55a65000f957dea65e0ab4b2f80578c7eec20251 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 55a6500 Update to version 1.8.0