bug#25032: 25.1; `bookmark-set-internal', `bookmark-set-no-overwrite'

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Tue, 2 Jul 2019 07:27:34 +0200
> Cc: 25032@debbugs.gnu.org
> 
> +If OVERWRITE-OR-PUSH is nil, then raise an error if there is

We use "signal an error".

> +already a bookmark named NAME; if `overwrite', then replace any
> +existing bookmark if there is one; if `push' then push the new
> +bookmark onto the bookmark alist.

It is generally better to precede a description of several optional
behaviors with a short summary:

  OVERWRITE-OR-PUSH controls what happens if there is already a
  bookmark by that NAME: nil means signal an error, `overwrite' means
  replace the existing bookmark, `push' means ...