finish: Future.shutdown;

--- a/src/Pure/Isar/session.ML	Thu Sep 11 21:04:07 2008 +0200
+++ b/src/Pure/Isar/session.ML	Thu Sep 11 21:04:09 2008 +0200
@@ -68,6 +68,7 @@
 fun finish () =
   (Output.accumulated_time ();
     ThyInfo.finish ();
+    Future.shutdown ();
     Present.finish ();
     session_finished := true);