bug#67661: 30.0.50; *Completions* has started popping up for icomplete-in-buffer

[Juri Linkov]

> 1. emacs -q
> 2. (setopt icomplete-in-buffer t)
> 3. M-x icomplete-mode
> 4. M-x eshell
> 5. try to tab-complete something where there is more than one possible
>    completion, e.g. ls<TAB> in a directory with many files.
>
> Previously you would get the icomplete in buffer completion.
> Now, additionally, *Completions* pops up, but it doesn't make sense to
> have both.

It's possible to hide *Completions* when icomplete-mode is enabled,
but I'm not sure if everyone will like this.  For example,
I'm using both icomplete-mode and the *Completions* buffer
at the same time in the minibuffer.  And in a regular buffer
we should keep for users the ability to pop up *Completions*
in addition to in-buffer completions.

Maybe the best solution would be to use something like
in completion-preview-mode where you can use in-buffer
completions and still be able to type M-C-i to pop up
the *Completions* buffer.