$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-polymaking.git /var/lib/mock/f40-build-2703683-70848/root/chroot_tmpdir/scmroot/gap-pkg-polymaking
Cloning into '/var/lib/mock/f40-build-2703683-70848/root/chroot_tmpdir/scmroot/gap-pkg-polymaking'...
$ git fetch origin 0643cafc39a87158357b0efdbd27aaa9357f38bd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-polymaking
 * [new ref]         0643cafc39a87158357b0efdbd27aaa9357f38bd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0643caf Rebuild for gap 4.13.0