docs: def info_file(distro=None):
      """Return default distroinfo info file"""
      if not distro:
          distro = cfg['DISTRO']
      info_file_conf = distro.upper() + 'INFO_FILE'
      try:
          return cfg[info_file_conf]
      except KeyError:
          raise exception.InvalidUsage(
              why="Couldn't find config option %s for distro: %s"
                  % (info_file_conf, distro))