excursion: interactive if debug;

--- a/src/Pure/Isar/toplevel.ML	Fri Sep 09 20:37:00 2005 +0200
+++ b/src/Pure/Isar/toplevel.ML	Sun Sep 11 20:02:51 2005 +0200
@@ -574,7 +574,7 @@
 
 fun excur [] x = x
   | excur ((tr, pr) :: trs) (st, res) =
-      (case apply false tr st of
+      (case apply (! debug) tr st of
         SOME (st', NONE) =>
           excur trs (st', transform_error (fn () => pr st st' res) () handle exn =>
             raise EXCURSION_FAIL (exn, "Presentation failed\n" ^ at_command tr))