o Security fixes:
    - Directory authorities now use data collected from rephist when
      choosing whether to assign the HSDir flag to relays, instead of
      trusting the uptime value the relay reports in its descriptor.
      This helps prevent an attack where a small set of nodes with
      frequently-changing identity keys can blackhole a hidden service.
      (Only authorities need upgrade; others will be fine once they do.)
      Bugfix on 0.2.0.10-alpha; fixes bug 2709.