o Minor bugfixes:
    - Convert an assert in the pathbias code to a log message. Assert
      appears to only be triggerable by Tor2Web mode. Fixes bug 6866;
      bugfix on 0.2.3.17-beta.
    - Disable the use of Guard nodes when in Tor2WebMode. Guard usage
      by Tor2Web clients allows hidden services to identity tor2web
      clients through their repeated selection of the same rendezvous
      and introduction point circuit endpoints (their guards). Fixes
      bug 6888.