bug#44950: 28.0.50; 24-bit colors not used in terminal with emacsclient

[Eli Zaretskii]

> From: Tim Ruffing <crypto@timruffing.de>
> Cc: 44950@debbugs.gnu.org
> Date: Mon, 31 May 2021 16:06:55 +0200
> 
> I think what tastytea is saying is that when emacs checks the env
> variable COLORTERM, it uses the environment of the server and not the
> one of emacsclient. And yes, that's just a bug. emacsclient should read
> that variable and pass it to server. But this requires new code because
> it breaks with the pattern of using terminfo to detect term support.
> 
> So the terminfo detection is currently more reliable. Would you be
> willing to accept something like the attached patch? This will improve
> detection without relying on COLORTERM, which should make the situation
> already much better. Tc is in the terminfo of many terminals, see
> https://gist.github.com/XVilka/8346728 .

That sounds like a kludge to me, of which we already have quite a few
there (the COLORTERM thing is already a kludge).  Do we really have to
add one more trick, just to paper over bad terminfo data?  Why don't
these terminals get their act together and fix their terminfo?