go http 请求解析body err: invalid character 'ï' looking for beginning of value

• 错误

  http 请求解析body出错：

  invalid character 'ï' looking for beginning of value
  

• 原因

  The server is sending you a UTF-8 text 
  string with a Byte Order Mark (BOM). 
  The BOM identifies that the text is UTF-8 encoded,
  but it should be removed before decoding.
  

• 解决

  在unmarshal之前将服务器返回的body处理一下:

   // Or []byte{239, 187, 191}
  body = bytes.TrimPrefix(body, []byte("\xef\xbb\xbf"))