bug#62847: 29.0.90; Propertized space in Org Agenda's mode-name

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: gusbrs.2016@gmail.com, 62847@debbugs.gnu.org
> Date: Sat, 15 Apr 2023 10:40:36 +0000
> 
> > What happens if you display mode-name inside org-agenda-set-mode-name:
> > does it have the properties there already?
> 
> First time, it does not. From the second agenda rebuild onward, the
> properties are there.

So maybe replace " " with (copy-sequence " ").