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

[Sebastian Tennant <sdt@sebyte.me>]

Quoth Robert Pluim <rpluim@gmail.com>
on Sat, 18 Mar 2023 12:38:32 +0100:
>> […]  If you discard the ‘screen.’ prefix by explicitly setting TERM
>> in your .screenrc; for example:
>>
>>  term xterm-256color
>>
>> it makes no difference, i.e. colours are still broken (when
>> COLORTERM is set to ‘truecolour’).
>
> Hmm, I get 24-bit colour in that case. Presumably because screen +
> gnome-terminal supports it.

It seems my version of screen was too old and truecolor is not
supported.

I've now built and installed screen ‘master’ (4.99) and the problem is
resolved, i.e. provided my .screenrc includes the line ‘truecolor on’,
colours work fine with COLORTERM set to ‘truecolor’, or not set at
all.

Sorry about all this.  Many months ago, I built screen from master and
ran it to see if it made a difference.  I concluded then that it
didn't and I think this must have been because I didn't actually
install the version I built.  This meant that the relevant entries
under /usr/lib/terminfo/s were not written/updated.

In any case, we've established one thing for certain, the version of
screen shipped by Debian bullseye (stable) does not support truecolor.
Most strange is the fact that, according to dpkg, the version shipped
is 4.8.0:

 $ dpkg -l | grep screen
 ii  screen  4.8.0-6  amd64 terminal multiplexer with VT100/ANSI…
             ^^^^^

but screen itself reports:

 $ screen --version
 Screen version 4.08.00 (GNU) 05-Feb-20
                ^^^^

which makes no sense at all!

According to:

 https://packages.debian.org/search?keywords=screen

Debian bookworm (the next stable release) will ship screen version
4.9.0.  I've downloaded the deb and grepped the manpage and the string
"truecolor" is nowhere to be found so it looks as if screen shipped by
Debian will lack support for truecolor for some years to come.