better display if command exits successfully.

go/qst.go

			r.cmd.Stdout = os.Stdout
			r.cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
			err := r.cmd.Run()
			log.Printf("%s finished: %s", r.shellCmd, err)
			var result interface{}
			if err != nil {
				result = err
			} else {
				result = r.cmd.ProcessState
			}
			log.Printf("%s finished: %s", r.shellCmd, result)
			time.Sleep(*delay)
			if !r.restart {