o Minor bugfixes (relay, address):
    - Don't trigger an IP change if no new valid IP can be found. Fixes bug
      40071; bugfix on 0.4.5.1-alpha.
    - When attempting to discover our IP, don't launch a descriptor fetch
      anymore but rather a simple test circuit since the address discovery is
      through the NETINFO cell now from the authorities. Fixes bug 40071; bugfix
      on 0.4.5.1-alpha.