Fix cancel_request() so that it adopts the change made for 3.1 regarding UNIX domain socket name. Before we thought backend_port = "" meant we should use UNIX domain socket, but now backend_port = "/" means UNIX domain socket.
Fix cancel_request() so that it adopts the change made for 3.1
regarding UNIX domain socket name. Before we thought backend_port = ""
meant we should use UNIX domain socket, but now backend_port = "/"
means UNIX domain socket.

treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres