$ git clone -n https://src.fedoraproject.org/rpms/firecracker.git /var/lib/mock/f39-build-2165405-50979/root/chroot_tmpdir/scmroot/firecracker
Cloning into '/var/lib/mock/f39-build-2165405-50979/root/chroot_tmpdir/scmroot/firecracker'...
$ git fetch origin 8789d016e19ff0bf2a4289eb630511f9a09894e3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/firecracker
 * [new ref]         8789d016e19ff0bf2a4289eb630511f9a09894e3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8789d01 Update to version 1.6.0