fixed error msg;

--- a/src/Pure/Isar/outer_syntax.ML	Wed Dec 22 20:29:19 1999 +0100
+++ b/src/Pure/Isar/outer_syntax.ML	Wed Dec 22 20:29:36 1999 +0100
@@ -329,7 +329,7 @@
   in
     if name <> name' then
       error ("Filename " ^ quote (Path.pack path) ^
-        " does not agree with theory name " ^ quote name)
+        " does not agree with theory name " ^ quote name')
     else (parents, map (Path.unpack o #1) files @ ml_file)
   end;