bug#23124: Two minibuffer resize related bugs

[martin rudalics]

> Let's start with a much simpler reproducer:
>
>    . emacs -Q
>    . Type "C-x" and wait until you see "C-x-" in the echo area
>    . Type "5 2"
>
> Result: a new frame is displayed, with both frames showing the
> "C-x 5 2" echo, which already sounds like a bug (only one frame should
> show it).
>
> Now type "C-p" -- only one of the two echo messages will disappear,
> the one in the non-selected window stays put.
>
> This didn't happen in Emacs 24.5, where the "C-x 5 2" echo is first
> cleared, and then redisplayed after the new frame is created.

So far it's just queer but after returning to the first frame and typing
C-p there repeatedly, "C-x 5 2" remains fixed in that frame's echo area.

> According to my testing, this problem appeared between Aug 31 and Sep
> 30 last year.

I love bisecting.  Especially when copyright lines change.

My recipe can be obviously simplified as well:

. emacs -Q to get the first frame
. Type C-x 5 2 to get the second frame
. Evaluate (message "x\ny") in the first frame
. Type C-p in the second frame

martin