$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-standardff.git /var/lib/mock/f38-build-side-42-init-devel-958813-28787/root/chroot_tmpdir/scmroot/gap-pkg-standardff
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-958813-28787/root/chroot_tmpdir/scmroot/gap-pkg-standardff'...
$ git fetch origin 13c603c4a4ef509b16307f4488dd3d83d50f704c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-standardff
 * [new ref]         13c603c4a4ef509b16307f4488dd3d83d50f704c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 13c603c Use the %gap_arches macro.