bug#1806: dired-pop-to-buffer in wrong place

[martin rudalics]

> I still think `split-window-vertically' is more appropriate because
> in a dired buffer it should unconditionally split the original window
> vertically.  In such situations `split-window-sensibly' is
> the wrong method
> with the wrong technique
>
> It displays a new window
> in the wrong place
> at the wrong time
>
> For the wrong reason and
> the wrong rhyme
>
> On the wrong day of
> the wrong week
>
> Wrong
>
> Wrong

Kto-to majskij prazdnik otmechajet ;-)

BTW, here we call a bridge day "Fenstertag" (window day) and since we
didn't have any bridge day this week it _was_ the wrong day of the wrong
week indeed ...

I don't have any problems hard-coding `split-window-vertically' in
`dired-pop-to-buffer' but:

(1) `split-window-sensibly' with `split-width-threshold' nil _should_ do
    `split-window-vertically' in the first place.  If it doesn't, I have
    a bug somewhere and must fix that.

(2) Someone might want `split-window-sensibly' do something special for
    dired buffers.

So please try to debug this and tell me why it doesn't split the window
vertically with a dired-window-only-frame configuration in the first
attempt.  It DTRT here for me.

martin

PS: It does not DTRT when there's another window below because it does
not restore the original window layout when the temporary window is
closed.   But that's another story ...