src/Pure/Tools/build.scala

             List("ML_Heap.save_child " +
               ML_Syntax.print_string_bytes(File.platform_path(store.output_heap(session_name))))
           }
           else Nil
 
-        if (options.bool("pide_build")) {
+        if (options.bool("pide_session")) {
           val resources = new Resources(sessions_structure, deps(parent))
           val session = new Session(options, resources)
 
           val build_session_errors: Promise[List[String]] = Future.promise
           val stdout = new StringBuilder(1000)