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

[martin rudalics]

> 1. Split window vertically.
>
>    In my case this branch is not selected because my window-height (79)
>    is less than split-height-threshold (80).

On my display this amounts to setting `split-height-threshold' nil.

> So display-buffer displays a list of dired files in the existing
> side window.
>
> I see one way to fix this - it is necessary to force
> the first branch to be selected.  It works when I tried
> the following lambda in dired-pop-to-buffer:
>
>     (lambda ()
>       (let ((split-height-threshold 0)
>             (split-width-threshold nil))
>         (with-selected-window old-window (funcall old-fun))))
>
> Setting split-height-threshold to 0 forces the vertical splitting.
> Setting split-width-threshold to nil prevents the horizontal splitting
> when the vertical splitting is not possible (the window is not splittable).

You convinced me.

Thanks, martin.