Fix the NEWS about my last commit: an unicode subclass can now override the
__unicode__ method (and not the __str__ method).

Simplify also the testcase.
diff --git a/Misc/NEWS b/Misc/NEWS
index 12db4af..385e341 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,7 +12,7 @@
 Core and Builtins
 -----------------
 
-- Issue #1583863: An unicode subclass can now override the __str__ method
+- Issue #1583863: An unicode subclass can now override the __unicode__ method
 
 - Issue #6474: Make error message from passing an inadequate number of keyword
   arguments to a function correct.