$ git clone -n https://src.fedoraproject.org/rpms/R-fs.git /var/lib/mock/f45-build-6106-346/root/chroot_tmpdir/scmroot/R-fs
Cloning into '/var/lib/mock/f45-build-6106-346/root/chroot_tmpdir/scmroot/R-fs'...
$ git fetch origin 4d1ae8a565f94beb93b1f968183c10daef2d8706:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-fs
 * [new ref]         4d1ae8a565f94beb93b1f968183c10daef2d8706 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4d1ae8a Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild