tuned message;

--- a/src/Pure/System/isabelle_process.ML	Fri Jun 01 12:45:22 2012 +0200
+++ b/src/Pure/System/isabelle_process.ML	Fri Jun 01 13:02:09 2012 +0200
@@ -57,7 +57,8 @@
     NONE => error ("Undefined Isabelle process command " ^ quote name)
   | SOME cmd =>
       (Runtime.debugging cmd args handle exn =>
-        error ("Isabelle process protocol failure: " ^ name ^ "\n" ^ ML_Compiler.exn_message exn)));
+        error ("Isabelle process protocol failure: " ^ quote name ^ "\n" ^
+          ML_Compiler.exn_message exn)));
 
 end;