libprocessgroup: Do not remove uid cgroups directory am: cc25244b

        std::this_thread::sleep_for(5ms);

    }

    // With the exception of boot or shutdown, system uid_ folders are always populated. Spinning

    // here would needlessly delay most pid removals. Additionally, once empty a uid_ cgroup won't

    // have processes hanging on it (we've already spun for all its pid_), so there's no need to

    // spin anyway.

    rmdir(uid_path.c_str());

    return ret;

}