bug#64152: 29.0.92; 'redirect-frame-focus' is broken

[Gregory Heytings]

> > That change has immediate consequences for interactions based on 
> > read_minibuf.  With emacs -Q evaluate (make-frame '((minibuffer . 
> > nil))) and in the frame created thusly type C-x C-f.  At this time it 
> > is impossible to access the minibuffer-less frame using C-x o, C-x 5 o, 
> > the window manager's Alt-TAB or any other key combination.  All these 
> > key combinations used to work in the given configuration ever since. 
> > With a minibuffer-only frames setup, the minibuffer window has become 
> > "modal".
>
> This works in Emacs 28, so the minibuffer-follows-selected-frame changes 
> aren't the culprit.  Bisection will be appreciated.

The culprit is 9cd72b02b6.