Add support Python 3.9

Author: shadchin

src/future/backports/xmlrpc/client.py

@@ -134,10 +134,11 @@
 from future.builtins import bytes, dict, int, range, str
 
 import base64
-# Py2.7 compatibility hack
-base64.encodebytes = base64.encodestring
-base64.decodebytes = base64.decodestring
 import sys
+if sys.version_info < (3, 9):
+    # Py2.7 compatibility hack
+    base64.encodebytes = base64.encodestring
+    base64.decodebytes = base64.decodestring
 import time
 from datetime import datetime
 from future.backports.http import client as http_client

src/future/moves/_dummy_thread.py

@@ -2,7 +2,10 @@
 from future.utils import PY3
 
 if PY3:
-    from _dummy_thread import *
+    try:
+        from _dummy_thread import *
+    except ImportError:
+        from _thread import *
 else:
     __future_module__ = True
     from dummy_thread import *

src/future/standard_library/__init__.py

@@ -125,7 +125,7 @@
            # 'Tkinter': 'tkinter',
            '_winreg': 'winreg',
            'thread': '_thread',
-           'dummy_thread': '_dummy_thread',
+           'dummy_thread': '_dummy_thread' if sys.version_info < (3, 9) else '_thread',
            # 'anydbm': 'dbm',   # causes infinite import loop
            # 'whichdb': 'dbm',  # causes infinite import loop
            # anydbm and whichdb are handled by fix_imports2