Issue #20571: skip test_readline() of test_codecs for Windows code page 65001.

The decoder does not support partial decoding yet for this code page.

Lib/test/test_codecs.py

@@ -890,6 +890,9 @@ class CP65001Test(ReadTest, unittest.TestCase):
                          "\U00010fff\uD800")
         self.assertTrue(codecs.lookup_error("surrogatepass"))
 
+    def test_readline(self):
+        self.skipTest("issue #20571: code page 65001 codec does not "
+                      "support partial decoder yet")
 
 
 class UTF7Test(ReadTest, unittest.TestCase):