o Major features:
    - If "UseBridges 1" is set and no bridges are configured, Tor will
      now refuse to build any circuits until some bridges are set.
      If "UseBridges auto" is set, Tor will use bridges if they are
      configured and we are not running as a server, but otherwise
      will make circuits as usual. The new default is "auto". Patch
      by anonym.