src/Pure/goal.ML

               val _ = status task [Isabelle_Markup.finished, Isabelle_Markup.joined];
               val _ =
                 (case result of
                   Exn.Res _ => ()
                 | Exn.Exn exn =>
-                    if Exn.is_interrupt exn then ()
+                    if id = 0 orelse Exn.is_interrupt exn then ()
                     else
                       (status task [Isabelle_Markup.failed];
                        Output.report (Markup.markup_only Isabelle_Markup.bad);
                        Output.error_msg (ML_Compiler.exn_message exn)));
               val _ = count_forked ~1;