diff -r e4903b803b8b -r e59220a075de src/Pure/Tools/check_keywords.scala
--- a/src/Pure/Tools/check_keywords.scala	Fri Mar 16 16:28:03 2018 +0100
+++ b/src/Pure/Tools/check_keywords.scala	Fri Mar 16 16:38:46 2018 +0100
@@ -41,7 +41,7 @@
 
     val bad =
       Par_List.map((arg: (String, Token.Pos)) => {
-        if (progress.stopped) throw Exn.Interrupt()
+        progress.expose_interrupt()
         conflicts(keywords, check, arg._1, arg._2)
       }, parallel_args).flatten