bug#50391: 28.0.50; json-read non-ascii data results in malformed string

[Philipp]

> Am 05.09.2021 um 06:19 schrieb Zhiwei Chen <condy0919@gmail.com>:
> 
> 
> When fetch json from youdao (a dict service in China).
> 
> #+begin_src elisp
> (url-retrieve
>  "https://dict.youdao.com/suggest?q=accumulate&le=eng&num=80&doctype=json";
>  (lambda (_status)
>    (goto-char (1+ url-http-end-of-headers))
>    (write-region (point) (point-max) "/tmp/acc1.json")))
> #+end_src
> 
> Then C-x C-f "/tmp/acc1.json", the file is correctly encoded without 
> 
> But If `json-read' then `json-insert', the file is malformed even if
> uchardet shows the encoding of the file is utf-8.
> 
> #+begin_src elisp
> (url-retrieve
>  "https://dict.youdao.com/suggest?q=accumulate&le=eng&num=80&doctype=json";
>  (lambda (_status)
>    (goto-char (1+ url-http-end-of-headers))
>    (let ((j (json-read)))
>    (with-temp-buffer
>      (json-insert j)
>      (write-region (point-min) (point-max) "/tmp/acc2.json")))))
> #+end_src

Does it work if you use the C JSON function (json-parse-buffer) for parsing?  
At least for me the two files are then identical.