bpo-40147: Move the check for duplicate keywords to the compiler (GH-19289)

diff --git a/Lib/test/test_metaclass.py b/Lib/test/test_metaclass.py
index e6fe20a..6edd899 100644
--- a/Lib/test/test_metaclass.py
+++ b/Lib/test/test_metaclass.py
@@ -128,7 +128,7 @@
     ...
     Traceback (most recent call last):
     [...]
-    SyntaxError: keyword argument repeated
+    SyntaxError: keyword argument repeated: metaclass
     >>>
 
 Another way.