src/Pure/Tools/build_job.scala

     sources_shasum: SHA1.Shasum,
     timeout: Time,
     old_time: Time,
     old_command_timings_blob: Bytes,
     build_uuid: String
-  ) {
-    override def toString: String = name
-  }
+  ) extends Library.Named
 
   class Session_Job private[Build_Job](
     build_context: Build_Process.Context,
     progress: Progress,
     log: Logger,