o Major bugfixes (circuit build, guard):
    - When considering upgrading circuits from "waiting for guard" to "open",
      always ignore the ones that are mark for close. Else, we can end up in
      the situation where a subsystem is notified of that circuit opening but
      still marked for close leading to undesirable behavior. Fixes bug 30871;
      bugfix on 0.3.0.1-alpha.