diff -r 869d50357a71 Lib/pydoc.py
--- a/Lib/pydoc.py	Sat Aug 31 21:14:00 2013 -0400
+++ b/Lib/pydoc.py	Mon Sep 02 18:47:44 2013 +0200
@@ -2059,10 +2059,13 @@
         def __init__(self, port, callback):
             host = 'localhost'
             self.address = (host, port)
-            self.url = 'http://%s:%d/' % (host, port)
             self.callback = callback
             self.base.__init__(self, self.address, self.handler)
 
+        @property
+        def url(self):
+            return "http://%s:%d" % self.server_address
+
         def serve_until_quit(self):
             import select
             self.quit = False
@@ -2345,7 +2348,8 @@
     Search for a keyword in the synopsis lines of all available modules.
 
 %s -p <port>
-    Start an HTTP server on the given port on the local machine.
+    Start an HTTP server on the given port on the local machine.  Port
+    number 0 can be used to get an arbitrary unused port.
 
 %s -g
     Pop up a graphical interface for finding and serving documentation.