o Minor bugfixes:
    - When a Tor client gets a "truncated" relay cell, the first byte of
      its payload specifies why the circuit was truncated. We were
      ignoring this 'reason' byte when tearing down the circuit, resulting
      in the controller not being told why the circuit closed. Now we
      pass the reason from the truncated cell to the controller. Bugfix
      on 0.1.2.3-alpha; fixes bug 7039.