Marc-Andre Lemburg:

Support for the new -U command line option option:
with the option enabled the Python compiler
interprets all "..." strings as u"..." (same with r"..." and
ur"...").

Python/compile.c

@@ -920,7 +920,7 @@ parsestr(s)
 			return NULL;
 		}
 	}
-	if (unicode) {
+	if (unicode || Py_UnicodeFlag) {
 		if (rawmode)
 			return PyUnicode_DecodeRawUnicodeEscape(
 				s, len, NULL);