src/Pure/System/isabelle_process.ML

         (fn mode => (mode @ default_modes1) |> fold (update op =) default_modes2);
 
     val channel = rendezvous ();
     val msg_channel = init_channels channel;
     val _ = Session.init_protocol_handlers ();
-    val _ = (loop |> Unsynchronized.setmp Toplevel.quiet true) channel;
+    val _ = loop channel;
   in Message_Channel.shutdown msg_channel end);
 
 fun init_fifos fifo1 fifo2 = init (fn () => System_Channel.fifo_rendezvous fifo1 fifo2);
 fun init_socket name = init (fn () => System_Channel.socket_rendezvous name);