message: bugfix: can not support capital pkcluster command
diff: @@ -265,12 +265,13 @@ void PikaClientConn::TryWriteResp() {
  void PikaClientConn::ExecRedisCmd(const PikaCmdArgsType& argv, std::shared_ptr<std::string> resp_ptr) {
  // get opt
  std::string opt = argv[0];
  + slash::StringToLower(opt);
  if (opt == kClusterPrefix) {
  if (argv.size() >= 2 ) {
  opt += argv[1];
  + slash::StringToLower(opt);
  }
  }
  - slash::StringToLower(opt);
  std::shared_ptr<Cmd> cmd_ptr = DoCmd(argv, opt, resp_ptr);
  // level == 0 or (cmd error) or (is_read)
  