$ git clone -n https://src.fedoraproject.org/rpms/maxima.git /var/lib/mock/f41-build-1211648-22574/root/chroot_tmpdir/scmroot/maxima
Cloning into '/var/lib/mock/f41-build-1211648-22574/root/chroot_tmpdir/scmroot/maxima'...
$ git fetch origin b6f3f24f697e9bc225abf138b99ba324445f20ea:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/maxima
 * [new ref]         b6f3f24f697e9bc225abf138b99ba324445f20ea -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6f3f24 Fix flatpak build