$ git clone -n https://src.fedoraproject.org/rpms/grc.git /var/lib/mock/f45-build-12999-444/root/chroot_tmpdir/scmroot/grc
Cloning into '/var/lib/mock/f45-build-12999-444/root/chroot_tmpdir/scmroot/grc'...
$ git fetch origin 6afa6cb802088bfc5c5abb8a72ce2c56c8181c53:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/grc
 * [new ref]         6afa6cb802088bfc5c5abb8a72ce2c56c8181c53 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6afa6cb Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild