o Major bugfixes (conflux):
    - Fix a relay-side assert crash caused by attempts to use a conflux
      circuit between circuit close and free, such that no legs were on
      the conflux set. Fixed by nulling out the stream's circuit
      back-pointer when the last leg is removed. Additional checks and
      log messages have been added to detect other cases. Fixes bug 40827;
      bugfix on 0.4.8.1-alpha.