Merge branch 'master' into handle-stream-native-coro

diff --cc tornado/tcpserver.py
Simple merge

diff --cc tornado/test/tcpserver_test.py
index ba43c76c6bc5697b9f95bdaa145bce68c86045c5,5c51c71f0ab72d57054bbb680a4c9b97c02a05ad..2d20b796cbc5ab609a195ceef7a1faa0d92c0b58
--- 1/tornado/test/tcpserver_test.py
--- 2/tornado/test/tcpserver_test.py
+++ b/tornado/test/tcpserver_test.py
@@@ -39,24 -39,10 +40,32 @@@ class TCPServerTest(AsyncTestCase)
              if client is not None:
                  client.close()
  
 +    @skipBefore35
 +    @gen_test
 +    def test_handle_stream_native_coroutine(self):
 +        # handle_stream may be a native coroutine.
 +
 +        namespace = exec_test(globals(), locals(), """
 +        class TestServer(TCPServer):
 +            async def handle_stream(self, stream, address):
 +                stream.write(b'data')
 +                stream.close()
 +        """)
 +
 +        sock, port = bind_unused_port()
 +        server = namespace['TestServer']()
 +        server.add_socket(sock)
 +        client = IOStream(socket.socket())
 +        yield client.connect(('localhost', port))
 +        result = yield client.read_until_close()
 +        self.assertEqual(result, b'data')
 +        server.stop()
 +        client.close()
++
+     def test_stop_twice(self):
+         sock, port = bind_unused_port()
+         server = TCPServer()
+         server.add_socket(sock)
+         server.stop()
+         server.stop()
+