Comment # 10 on bug 1209594 from Stefan Dirsch

Ok. I think I can add this additional 

  localectl set-x11-keymap $XKBLAYOUT $XKBMODEL $XKBVARIANT $XKBOPTIONS

call if XKBLAYOUT is set. The chance for a regression is low since more or less
nobody is trying to use "localectl set-x11-keymap ...". It's the first report
I've seen since this script exists.

BTW, localectl rewrites /etc/vconsole.conf itself. Don't try to figure out
when. It's asynchron via a deamon and only does that if current keyboard config
changes. No, not the one in /etc/vconsole.conf. Never ever try to write
/etc/vconsole.conf yourself.