bug#21391: 24.5; `thing-at-point' should return a string

[Eli Zaretskii]

> Cc: tino.calancha@gmail.com, 21391@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Fri, 11 Nov 2016 16:57:20 +0200
> 
> On 11.11.2016 16:51, Eli Zaretskii wrote:
> 
> > Improve it by describing whatever it is that is evident from the code
> > that is not evident from the doc string.
> 
> So we will enumerate how every built-in "thing" behaves?

No, we won't, not unless you and Tino say that's what you think should
be there.

> > I don't understand why.  It's not like we don't have other functions
> > that can return different kinds of objects.
> 
> Because there is no rhyme or reason in the current behavior, no matter 
> how you want to look at it.

The reason is that it existed in this form for the last 19 years.