Update test_wsgiref.py

Author: benediktjohannes

Lib/test/test_wsgiref.py

@@ -854,10 +854,8 @@ def testRaisesControlCharacters(self):
             with self.subTest(c0):
                 base = BaseHandler()
                 headers = [('x','y')]
-                headers.add_header("key", "val")
                 # HTAB (\x09) is allowed in values, but not in names.
                 if c0 == "\t":
-                    base['key'] = f"val{c0}"
                     base.start_response(f"key{c0}", headers)
                 else:
                     self.assertRaises(ValueError, base.start_response, f"key{c0}", headers)