$ git clone -n https://src.fedoraproject.org/rpms/R-tibble.git /var/lib/mock/f38-build-724399-99434/root/chroot_tmpdir/scmroot/R-tibble
Cloning into '/var/lib/mock/f38-build-724399-99434/root/chroot_tmpdir/scmroot/R-tibble'...
$ git fetch origin 0cca7c5ca7c186afd59aa0f82e3d9811cef09259:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-tibble
 * [new ref]         0cca7c5ca7c186afd59aa0f82e3d9811cef09259 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0cca7c5 Update to latest version