message: add SIGINT handler for pipeline server
diff: @@ -37,6 +37,11 @@ from paddle_serving_server.util import *
  from paddle_serving_server.env_check.run import check_env
  import cmd
  +def signal_handler(signal, frame):
  + print('Process stopped')
  + sys.exit(0)
  +
  +signal.signal(signal.SIGINT, signal_handler)
  # web_service.py is still used by Pipeline.
  def port_is_available(port):
  