Close the parent process' copy of the socket.

The parent process should close its copy of the socket descriptor.

src/bandwidth_tester.py

@@ -174,6 +174,8 @@ if __name__ == '__main__':
 			processes.append(p)
 			processes_map[conn_id] = p
 			p.start()
+			socket.close()
+			# close this process' copy of the socket
 		#
 		l = basic_protocols.ServerListener(endpoint, accept_callback)
 		#