$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-ace.git /var/lib/mock/f40-build-801710-143851/root/chroot_tmpdir/scmroot/gap-pkg-ace
Cloning into '/var/lib/mock/f40-build-801710-143851/root/chroot_tmpdir/scmroot/gap-pkg-ace'...
$ git fetch origin b40db469a041b535b0aa539c1a6196a4ef7d9807:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-ace
 * [new ref]         b40db469a041b535b0aa539c1a6196a4ef7d9807 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b40db46 Rebuild for gap 4.13.0