def set_config_value(sec, opt, value):
    """Set a config value.

    Only sets the value if the value is not founc of empty.

    """
    config = ConfigParser.RawConfigParser()
    config.read(CONFIG_FILE)

    if not config.has_option(sec, opt):
        config.set(sec, opt, value)
    elif config.get(sec, opt) == '':
        config.set(sec, opt, value)
    write_config(config)