$ git clone -n https://src.fedoraproject.org/rpms/R-doMC.git /var/lib/mock/f45-build-6059-346/root/chroot_tmpdir/scmroot/R-doMC
Cloning into '/var/lib/mock/f45-build-6059-346/root/chroot_tmpdir/scmroot/R-doMC'...
$ git fetch origin 8b93305f441462b801c6d0b8c8272f3a308c5a44:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-doMC
 * [new ref]         8b93305f441462b801c6d0b8c8272f3a308c5a44 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8b93305 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild