Prior to SERVER-87466, replanning consisted of manually enumerating plans, constructing a MultiPlanStage, and running trials all within the CachedPlanStage. Post-SERVER-87466, we return a non-OK Status back to get_executor which begins normal query processing from the start, notably excluding the possibility of invoking subplanning. We should see if we can invoke subplanning in replanning - there is the possibility that we pick a better plan.