improve error message from passing inadequate number of keyword arguments #6474

Note this removes the "non-keyword" or "keyword" phrases from these messages.
diff --git a/Lib/test/test_extcall.py b/Lib/test/test_extcall.py
index 3eea121..bb922c8 100644
--- a/Lib/test/test_extcall.py
+++ b/Lib/test/test_extcall.py
@@ -270,6 +270,15 @@
     ...     print a,b
     >>> f(**x)
     1 2
+
+A obscure message:
+
+    >>> def f(a, b):
+    ...    pass
+    >>> f(b=1)
+    Traceback (most recent call last):
+      ...
+    TypeError: f() takes exactly 2 arguments (1 given)
 """
 
 import unittest