bug#14829: 24.3; split-window-keep-point breaks shell tab completion

[martin rudalics]

> With `(setq split-window-keep-point t)` you will see the window split,
> with the top window scrolled to leave point just after the `a` in the
> middle of the window.  The bottom window will have the completions for
> aa.txt and ab.txt
>
> With `(setq split-window-keep-point nil)` you will not get any window
> split, but point will jump someplace higher up in the window (e.g. for
> me it jumps to just after the gg.txt line).

`split-window-below' here does

    (setq new-window (split-window nil size))
    (unless split-window-keep-point

so I don't understand how setting `split-window-keep-point' can affect
the decisison whether to split the window.

Does anyone know where this behavior comes from?

martin