bug#50409: describe-variable says variable was introduced in two different versions

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sun, 5 Sep 2021 20:11:24 +0200
> 
> describe-variable is saying that 'tab-first-completion' was introduced
> in both 27.1 and 28.1.
> 
> Steps to reproduce:
> 
> 0. emacs -Q
> 1. C-h v describe-variable RET
> 
> The help buffer now shows:
> 
> tab-first-completion is a variable defined in ‘indent.el’.
> 
> Its value is nil
> 
>   You can customize this variable.
>   This variable was introduced, or its default value was changed, in
>   version 27.1 of Emacs.
>   Probably introduced at or before Emacs version 28.1.

Thanks, fixed.