bug#51321: 29.0.50; date in modelines

[Eli Zaretskii]

> From: Niels Søndergaard <nisoni@algon.dk>
> Date: Thu, 21 Oct 2021 20:09:13 +0200
> Cc: Niels Søndergaard <nisoni@algon.dk>,
>  51321@debbugs.gnu.org
> 
> Actually I can´t figure put, ejere to look for it. I even tried to look in 
> the source, but it just confused me. I´ve looked in most of the documentation 
> without luck…

You are supposed to customize the option display-time-format.