tor/changes/bug18809

  o Major bugfixes (bootstrap):
    - Check if bootstrap consensus downloads are still needed
      when the linked connection attaches. This prevents tor
      making unnecessary begindir-style connections, which are
      the only directory connections tor clients make since
      the fix for 18483 was merged.
    - Fix some edge cases where consensus download connections
      may not have been closed, even though they were not needed.
      Related to fix  18809.
    - Make relays retry consensus downloads the correct number of
      times, rather than the more aggressive client retry count.
      Fixes part of ticket 18809.
    - Stop downloading consensuses when we have a consensus,
      even if we don't have all the certificates for it yet.
      Fixes bug 18809; bugfix on 0.2.8.1-alpha.
      Patches by arma and teor.