  o Minor bugfixes:
    - Avoid leaking IPv6 policy content if we fail to format it into
      a router descriptor. Spotted by Coverity. Fixes part of 7816;
      bugfix on 0.2.4.7-alpha.

    - Avoid leaking memory if we fail to compute a consensus signature
      or we generated a consensus we couldn't parse. Spotted by Coverity.
      Fixes part of 7816; bugfix on 0.2.0.5-alpha.
