Issue #19543: Emit deprecation warning for known non-text encodings.

Backported issues #19619: encode() and decode() methods and constructors
of str, unicode and bytearray classes now emit deprecation warning for known
non-text encodings when Python is ran with the -3 option.

Backported issues #20404: io.TextIOWrapper (and hence io.open()) now uses the
internal codec marking system added to emit deprecation warning for known non-text
encodings at stream construction time when Python is ran with the -3 option.
diff --git a/Lib/test/test_calendar.py b/Lib/test/test_calendar.py
index 5692642..46c4a6f 100644
--- a/Lib/test/test_calendar.py
+++ b/Lib/test/test_calendar.py
@@ -513,8 +513,8 @@
     def test_option_encoding(self):
         self.assertFailure('-e')
         self.assertFailure('--encoding')
-        stdout = self.run_ok('--encoding', 'rot-13', '2004')
-        self.assertEqual(stdout.strip(), conv(result_2004_text.encode('rot-13')).strip())
+        stdout = self.run_ok('--encoding', 'utf-16-le', '2004')
+        self.assertEqual(stdout.strip(), conv(result_2004_text.encode('utf-16-le')).strip())
 
     def test_option_locale(self):
         self.assertFailure('-L')