src/Pure/Tools/build_schedule.scala

 
     override def next_node_info(state: Build_Process.State, session_name: String): Node_Info =
       _schedule.graph.get_node(session_name).node_info
 
     override def next_jobs(state: Build_Process.State): List[String] =
-      if (progress.stopped || _schedule.is_outdated(build_options, state)) Nil
-      else _schedule.next(hostname, state)
+      if (progress.stopped || _schedule.is_empty) Nil else _schedule.next(hostname, state)
   }
 
   abstract class Scheduler_Build_Process(
     build_context: Build.Context,
     build_progress: Progress,