$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-orb.git /var/lib/mock/f38-build-side-42-init-devel-970941-28812/root/chroot_tmpdir/scmroot/gap-pkg-orb
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-970941-28812/root/chroot_tmpdir/scmroot/gap-pkg-orb'...
$ git fetch origin 66ffb3b20e452a4d256ca84a5328126532a27505:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-orb
 * [new ref]         66ffb3b20e452a4d256ca84a5328126532a27505 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 66ffb3b Use the %gap_arches macro.