Get rid of some dead code and unneeded XXX comments by Neal.

Modules/datetimemodule.c

@@ -1159,17 +1159,12 @@ make_Zreplacement(PyObject *object, PyObject *tzinfoarg)
 	if (Zreplacement == NULL)
 		return NULL;
 	if (PyUnicode_Check(Zreplacement)) {
-		/* XXX(nnorwitz): this is really convoluted, is it correct? */
 		PyObject *Zreplacement2 =
 			_PyUnicode_AsDefaultEncodedString(Zreplacement, NULL);
 		if (Zreplacement2 == NULL)
 			return NULL;
 		Py_INCREF(Zreplacement2);
-		/* Zreplacement is owned, but Zreplacement2 is borrowed.
-		   If they are different, we have to release Zreplacement. */
-		if (Zreplacement != Zreplacement2) {
-			Py_DECREF(Zreplacement);
-		}
+		Py_DECREF(Zreplacement);
 		Zreplacement = Zreplacement2;
 	}
 	if (!PyString_Check(Zreplacement)) {

Objects/unicodeobject.c

@@ -1189,17 +1189,9 @@ PyObject *_PyUnicode_AsDefaultEncodedString(PyObject *unicode,
         return v;
     if (errors != NULL)
         Py_FatalError("non-NULL encoding in _PyUnicode_AsDefaultEncodedString");
-    /* XXX(nnorwitz): errors will always be NULL due to the check above.
-	Should this check and the else be removed since it's dead code?
-     */
-    if (errors == NULL) {
-        b = PyUnicode_EncodeUTF8(PyUnicode_AS_UNICODE(unicode),
-                                 PyUnicode_GET_SIZE(unicode),
-                                 NULL);
-    }
-    else {
-        b = PyUnicode_AsEncodedString(unicode, NULL, errors);
-    }
+    b = PyUnicode_EncodeUTF8(PyUnicode_AS_UNICODE(unicode),
+                             PyUnicode_GET_SIZE(unicode),
+                             NULL);
     if (!b)
         return NULL;
     v = PyString_FromStringAndSize(PyBytes_AsString(b),