Roger points out that most people do not set UpdateBridgesFromAuthority

  Tor 0.2.9.2-alpha continues development of the 0.2.9 series with

  several new features and bugfixes. It also includes an important

  authority update and an important bugfix from 0.2.8.7. Everyone who

  sets the ReachableAddresses option, all bridges, and all bridge users

  are strongly encouraged to upgrade to 0.2.8.7, or to 0.2.9.2-alpha.

  sets the ReachableAddresses option, and all bridges, are strongly

  encouraged to upgrade to 0.2.8.7, or to 0.2.9.2-alpha.

  o Directory authority changes (also in 0.2.8.7):

    - The "Tonga" bridge authority has been retired; the new bridge