code: func (nc *Conn) cloneMsgArg() {
  	nc.ps.argBuf = nc.ps.scratch[:0]
  	nc.ps.argBuf = append(nc.ps.argBuf, nc.ps.ma.subject...)
  	nc.ps.argBuf = append(nc.ps.argBuf, nc.ps.ma.reply...)
  	nc.ps.ma.subject = nc.ps.argBuf[:len(nc.ps.ma.subject)]
  	if nc.ps.ma.reply != nil {
  		nc.ps.ma.reply = nc.ps.argBuf[len(nc.ps.ma.subject):]
  	}
  }
docs: // cloneMsgArg is used when the split buffer scenario has the pubArg in the existing read buffer, but
  // we need to hold onto it into the next read.