src/Pure/System/invoke_scala.ML

--- a/src/Pure/System/invoke_scala.ML	Wed Jun 21 22:57:40 2017 +0200
+++ b/src/Pure/System/invoke_scala.ML	Thu Jun 22 14:27:13 2017 +0200
@@ -31,7 +31,7 @@
   let
     val id = new_id ();
     fun abort () = Output.protocol_message (Markup.cancel_scala id) [];
-    val promise = Future.promise abort : string future;
+    val promise = Future.promise_name "invoke_scala" abort : string future;
     val _ = Synchronized.change promises (Symtab.update (id, promise));
     val _ = Output.protocol_message (Markup.invoke_scala name id) [arg];
   in promise end;