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

[Dmitry Gutov]

On 11/25/2015 07:49 PM, martin rudalics wrote:
> Setting a breakpoint in gdb currently fails with a message like
>
>
> Debugger entered--Lisp error: (json-string-format "doesn't start with
> `\"'!")
>    signal(json-string-format ("doesn't start with `\"'!"))
>    json-read-string()
>    json-read-object()
>    apply(json-read-object nil)
>    json-read()
>    json-read-object()
>    apply(json-read-object nil)
>    json-read()

Could you find out the contents of the buffer it's trying to read?

A bisect would be great too, of course. Is this a recent problem?