bug#22012: 25.1.50; gdb broken by (json-string-format "doesn't start with `\"'!")

[Eli Zaretskii]

> Date: Sat, 28 Nov 2015 15:13:14 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: dgutov@yandex.ru, 22012@debbugs.gnu.org
> 
>  > Can you switch to that buffer and look what's at point?  And while at
>  > that, post here the full contents of that buffer?
> 
> It just happened again while debugging xdisp.c.  The buffer is called
> *partial-output-emacs.exe* (with a leading space) it contains 2295
> characters and its position of point was 2.  The contents of that buffer
> are hopefully in the attached file partial-output-emacs.txt (for reasons
> that elude me I was not able to inline them with Thunderbird).

There are null bytes after `{"width":"4","alignment":"-1",'.  So it's
a small wonder that json.el chokes.  IOW, this is not a problem with
either json.el not gdb-mi.el, but a much more fundamental problem with
low-level Emacs functions that insert text into a buffer.

When did you last update from the emacs-25 branch?