$ git clone -n https://src.fedoraproject.org/rpms/linbox.git /var/lib/mock/f42-build-863054-171350/root/chroot_tmpdir/scmroot/linbox
Cloning into '/var/lib/mock/f42-build-863054-171350/root/chroot_tmpdir/scmroot/linbox'...
$ git fetch origin 6176a288453630f96e90af3994cf969cb26fb3ed:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/linbox
 * [new ref]         6176a288453630f96e90af3994cf969cb26fb3ed -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6176a28 Rebuild for libfplll 5.5.0