o Major bugfixes (circuit build timeout):
    - Under certain conditions, the circuit build timeout history
      could become filled with "abandoned" entries, which would block
      updating the timeout as network conditions change. This could
      cause connectivity failure if the timeout value became stuck
      at a sufficiently low value. Missing first-hop timeout accounting
      could also prevent the timeout from being reset, when these failures
      happen at the first hop of the circuit. We've corrected the first-hop
      accounting, and have fixed two sources of excessive abandoned
      timeout entries, and added additional reset handling when the timeout
      history becomes full of abandoned timeout measurements. We've also
      added diagnostic log messages to help detect any potential
      remaining cases of timeout miscounting and abandonment accumulation.
      Fixes bug 41420; bugfix on 0.2.2.14-alpha.