o Minor bugfixes (bridges):
    - When we don't yet have a descriptor for one of our bridges, disable
      the entry guard retry schedule on that bridge. The entry guard retry
      schedule and the bridge descriptor retry schedule can conflict,
      e.g. where we mark a bridge as "maybe up" yet we don't try to fetch
      its descriptor yet, leading Tor to wait (refusing to do anything)
      until it becomes time to fetch the descriptor. Fixes bug 40497;
      bugfix on 0.3.0.3-alpha.