$ git clone -n https://src.fedoraproject.org/rpms/mlpack.git /var/lib/mock/f39-build-2451956-61041/root/chroot_tmpdir/scmroot/mlpack
Cloning into '/var/lib/mock/f39-build-2451956-61041/root/chroot_tmpdir/scmroot/mlpack'...
$ git fetch origin 9012d855ad2d9b75dda0f066843db56f616c3c27:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mlpack
 * [new ref]         9012d855ad2d9b75dda0f066843db56f616c3c27 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9012d85 Oops, add new source.