$ git clone -n https://src.fedoraproject.org/rpms/R-rematch2.git /var/lib/mock/f45-build-6368-348/root/chroot_tmpdir/scmroot/R-rematch2
Cloning into '/var/lib/mock/f45-build-6368-348/root/chroot_tmpdir/scmroot/R-rematch2'...
$ git fetch origin d6373567a2d59e6fb36d67090f5279f851d9b8e5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-rematch2
 * [new ref]         d6373567a2d59e6fb36d67090f5279f851d9b8e5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d637356 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild