src/Pure/Tools/build_job.scala

     val old_command_timings_blob: Bytes
   ) {
     override def toString: String = name
   }
 
-  class Build_Session(
+  class Session_Job(
     progress: Progress,
     verbose: Boolean,
     session_background: Sessions.Background,
     session_heaps: List[Path],
     store: Sessions.Store,