Merge from 3.3

Issue #22421 - Secure pydoc server run. Bind it to localhost instead of all interfaces.
diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 37abf67..5393426 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -2178,8 +2178,8 @@
     class DocServer(http.server.HTTPServer):
 
         def __init__(self, port, callback):
-            self.host = (sys.platform == 'mac') and '127.0.0.1' or 'localhost'
-            self.address = ('', port)
+            self.host = 'localhost'
+            self.address = (self.host, port)
             self.callback = callback
             self.base.__init__(self, self.address, self.handler)
             self.quit = False
diff --git a/Lib/test/test_pydoc.py b/Lib/test/test_pydoc.py
index a513fa6..8bf9b20 100644
--- a/Lib/test/test_pydoc.py
+++ b/Lib/test/test_pydoc.py
@@ -803,6 +803,8 @@
             return text
 
         serverthread = pydoc._start_server(my_url_handler, port=0)
+        self.assertIn('localhost', serverthread.docserver.address)
+
         starttime = time.time()
         timeout = 1  #seconds