RE: when deleting in minibuffer, don't change kill-ring

[Drew Adams]

> how to prohibit kill-ring being changed, when I press
> "backspace" key in minibuffer?

It is _not_ changed.  Provide a recipe, starting from emacs -Q.

If you do need to change the binding of the key for some reason, then do so in
each of the minibuffer key maps.  E.g.,

(define minibuffer-local-must-match-map (kbd "DEL")
        'backward-delete-char)
etc.

But AFAICT, the global binding of DEL (and <backspace>) is in effect in the
minibuffer, and the global binding does not kill a char, it deletes it.