bug#23750: 25.0.95; bug in url-retrieve or json.el

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 23750@debbugs.gnu.org, Leo Liu <sdl.web@gmail.com>,
>  Eli Zaretskii <eliz@gnu.org>
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Sun, 19 Jun 2016 21:14:55 +0300
> 
> On 06/14/2016 03:30 AM, Stefan Monnier wrote:
> 
> > Can't remember why I did so.  My best guess is that I tried to mimick
> > some earlier behavior.
> 
> OK, thanks anyway. I've pushed the patch to master as 
> 2ede29575fa22eb7c265117d7511cff9fe02c606.
> 
> Eli, could we have it emacs-25 as well? It's not critical, but it should 
> make the life of our users easier to flagging problems with the usage of 
> url-http earlier, in a more appropriate place, with an error, rather 
> than leaving that up to them to deduce why their HTTP server truncates 
> the request body.

I'd need a very detailed description of the bug, and why this
particular solution was used.  IME, neither string-to-unibyte not
string-as-unibyte should ever be used in applications, their use is
more often than not a sign of some basic misunderstanding of text
encoding.  For starters, how come 8-bit bytes wind up in that
function, and what do they stand for?