src/Pure/Tools/main.scala

           val session = Isabelle_System.default_logic(
             Isabelle_System.getenv("JEDIT_LOGIC"),
             options.string("jedit_logic"))
 
           if (Build.build(options = options, build_heap = true, no_build = true,
-              dirs = dirs, sessions = List(session)) == 0)
+              dirs = dirs, system_mode = system_mode, sessions = List(session)) == 0)
             system_dialog.return_code(0)
           else {
             system_dialog.title("Isabelle build (" + Isabelle_System.getenv("ML_IDENTIFIER") + ")")
             system_dialog.echo("Build started for Isabelle/" + session + " ...")