$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-genss.git /var/lib/mock/f38-build-side-42-init-devel-912295-28695/root/chroot_tmpdir/scmroot/gap-pkg-genss
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-912295-28695/root/chroot_tmpdir/scmroot/gap-pkg-genss'...
$ git fetch origin 678c83dd2882f7f4cf2ab8f69ffebbecc08338a9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-genss
 * [new ref]         678c83dd2882f7f4cf2ab8f69ffebbecc08338a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 678c83d Use the %gap_arches macro.