bug#8188: 24.0.50; incorrect column width in *Completions* buffer

[Florian Beck]

emacs -q
(split-window-horizontally 30)
M-x o
C-h f [TAB]

Result: The second column is obscured, only the first is visible.

[SPC] [DEL] [TAB]

Now the columns are calculated correctly.

The reasons is that `window' in `completion--insert-strings' is set to 
nil unless a *Completions* buffer is already displayed. (minibuffer.el, 
line 951).

Florian Beck