$ git clone -n https://src.fedoraproject.org/rpms/R-rlang.git /var/lib/mock/f41-build-710602-13019/root/chroot_tmpdir/scmroot/R-rlang
Cloning into '/var/lib/mock/f41-build-710602-13019/root/chroot_tmpdir/scmroot/R-rlang'...
$ git fetch origin 2d7b5caecc9a796b379cbcb2fb9c363f527d4e78:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-rlang
 * [new ref]         2d7b5caecc9a796b379cbcb2fb9c363f527d4e78 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2d7b5ca Update to latest version