$ git clone -n https://src.fedoraproject.org/rpms/R-sass.git /var/lib/mock/f45-build-6377-348/root/chroot_tmpdir/scmroot/R-sass
Cloning into '/var/lib/mock/f45-build-6377-348/root/chroot_tmpdir/scmroot/R-sass'...
$ git fetch origin 4bd255ee5d14b6487c941fc8d81d906373537a19:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-sass
 * [new ref]         4bd255ee5d14b6487c941fc8d81d906373537a19 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4bd255e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild