bug#38645: 26.3; minibuffer input is called with multi-line window when multi-line message is shown

[martin rudalics <rudalics@gmx.at>]

 > Martin, what do you think about the following fix?  Is it correct, and
 > if so, safe enough for the release branch?

It seems "correct" in the sense that our doc of 'resize-mini-windows'
nowhere contradicts any such interpretation.  It should be "safe" in
the sense that failing to always resize the minibuffer window exactly
and falling back on 'grow-only' should not do any harm since otherwise
we'd have a bug in the 'grow-only' part of the code.

But I'm too silly to understand why the minibuffer window does not
re-grow in the first place after having shown the result of C-x C-e.
Can you enlighten me?

martin, who just noted that the recently added (to master)

       Lisp_Object str = build_string ("Command attempted to use minibuffer"
                                       "while in minibuffer");

produces

"Command attempted to use minibufferwhile in minibuffer"

martin