$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-polenta.git /var/lib/mock/f40-build-2590778-62637/root/chroot_tmpdir/scmroot/gap-pkg-polenta
Cloning into '/var/lib/mock/f40-build-2590778-62637/root/chroot_tmpdir/scmroot/gap-pkg-polenta'...
$ git fetch origin cd6c6ff3e824e0eb7ddcde0d87acb71c9cddffd5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-polenta
 * [new ref]         cd6c6ff3e824e0eb7ddcde0d87acb71c9cddffd5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cd6c6ff Rebuild for gap 4.13.0