Issue #8498: In socket.accept(), allow to specify 0 as a backlog value in

order to accept exactly one connection.  Patch by Daniel Evers.

Lib/test/test_socket.py

@@ -788,6 +788,13 @@ def test_name_closed_socketio(self):
             fp.close()
             self.assertEqual(repr(fp), "<_io.BufferedReader name=-1>")
 
+    def testListenBacklog0(self):
+        srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        srv.bind((HOST, 0))
+        # backlog = 0
+        srv.listen(0)
+        srv.close()
+
 
 @unittest.skipUnless(thread, 'Threading required for this test.')
 class BasicTCPTest(SocketConnectedTest):