Make test_new pass.
diff --git a/Lib/test/test_new.py b/Lib/test/test_new.py
index 797a8c3..c919621 100644
--- a/Lib/test/test_new.py
+++ b/Lib/test/test_new.py
@@ -143,7 +143,7 @@
                 firstlineno, lnotab)
 
             # new.code used to be a way to mutate a tuple...
-            class S(str):
+            class S(str8):
                 pass
             t = (S("ab"),)
             d = new.code(argcount, kwonlyargcount, nlocals, stacksize,