*  * The first race is between plan0 and plan1, with a 250 ms head start for plan0.
   *  * The second race is between plan2 and plan3, with a 250 ms head start for plan2.
   *
   * We get plan0 and plan1 from the route planner.
   * We get plan2 as a follow-up to plan1, typically retry the same IP but different TLS.
   * We get plan3 as a retry of plan0, which was canceled when it lost the race.
   *