bug#62237: 28.1 or higher: 24-bit true color breaks colours in Emacsen built without X under GNU Screen

[Eli Zaretskii <eliz@gnu.org>]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: sdt@sebyte.me,  62237@debbugs.gnu.org
> Date: Sat, 18 Mar 2023 11:02:16 +0100
> 
> >>>>> On Sat, 18 Mar 2023 11:09:10 +0200, Eli Zaretskii <eliz@gnu.org> said:
> 
>     >> From: Robert Pluim <rpluim@gmail.com>
>     >> Cc: sdt@sebyte.me,  62237@debbugs.gnu.org
>     >> Date: Sat, 18 Mar 2023 10:05:49 +0100
>     >> 
>     >> >>>>> On Fri, 17 Mar 2023 20:55:23 +0200, Eli Zaretskii <eliz@gnu.org> said:
>     >> >> machines you are able to do a rlogin and still keep the  correct  term‐
>     --> cap/terminfo  entry.  The terminal name is put in the $TERM variable of
>     >> >> all new windows.  Screen also sets the $TERMCAP variable reflecting the
>     >> >> capabilities of the virtual terminal emulated. Notice that, however, on
>     >> >> machines using the terminfo database this variable has no effect.  Fur‐
>     >> >> thermore, the variable $WINDOW is set to the window number of each win‐
>     >> >> dow.
>     >> 
>     Eli> This seems to tell how 'screen' figures out the terminal name, not how
>     Eli> it sets TERM.  I asked who and why sets TERM to screen.SOMETHING.
>     >> 
>     >> screen does: "The terminal name is put in the $TERM variable of all new windows."
> 
>     Eli> So how did Emacs ever succeed to work inside screen, then?  AFAIK, we
>     Eli> never supported this form of TERM's value.  Is this something
>     Eli> relatively new?
> 
> I donʼt know, Iʼm a tmuxian ;-)
> 
> Note that emacs works fine, itʼs just the colours that are off, and
> people sshʼing in to use screen would tend to set TERM themselves
> anyway.

Then I guess we should install your proposed fix in init_tty.