$ git clone -n https://src.fedoraproject.org/rpms/compiler-rt18.git /var/lib/mock/f41-build-side-1-3102014-39350/root/chroot_tmpdir/scmroot/compiler-rt18
Cloning into '/var/lib/mock/f41-build-side-1-3102014-39350/root/chroot_tmpdir/scmroot/compiler-rt18'...
$ git fetch origin fded11ced8bd139958c96feb1e59d38c18b2b002:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/compiler-rt18
 * [new ref]         fded11ced8bd139958c96feb1e59d38c18b2b002 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fded11c Update to 18.1.8