bug#34639: 26.1; Custom themes break terminal when switching to org-mode

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Date: Mon, 25 Feb 2019 21:59:15 -0500
> Cc: kisik21@fireburn.ru, 34639@debbugs.gnu.org
> 
>   > FWIW, Emacs 26 introduced built-in line numbers via
>   > display-line-numbers-mode, making linum-mode obsolete
>   > (I wonder whether linum-mode should be labelled as such).
> 
> How about making linum-mode an interface for this?

Not really possible, since there are user-visible differences.  I left
linum-mode not obsolete because some people might decide not to switch
due to those differences.  We should revisit this issue a few years
from now, IMO.