src/Pure/Thy/thy_load.ML

     val (results, thy) = cond_timeit time "" (fn () => Toplevel.excursion elements);
     val _ = if time then writeln ("**** Finished theory " ^ quote name ^ " ****\n") else ();
 
     val present =
       singleton (Future.cond_forks {name = "Outer_Syntax.present:" ^ name, group = NONE,
-        deps = map Future.task_of results, pri = 0})
+        deps = map Future.task_of results, pri = 0, interrupts = true})
       (fn () =>
         Thy_Output.present_thy (#1 lexs) Keyword.command_tags
           (Outer_Syntax.is_markup outer_syntax)
           (maps Future.join results) toks
         |> Buffer.content