bug#74438: 29.1; global-mark-ring does not work as described

[Eli Zaretskii <eliz@gnu.org>]

> From: Nikolay Kudryavtsev <nikolay.kudryavtsev@gmail.com>
> Date: Wed, 20 Nov 2024 13:18:00 +0300
> 
> Emacs won't allow you to set multiple marks in the same position, it's just going to activate the current mark.
> Hence your reproduction recipe can be simplified to:
> 
> 1 C-x C-f foo
> 2 C-SPC => Mark set
> 3 C-SPC => Mark deactivated
> 4 C-SPC => Mark activated
> 5 C-SPC => Mark deactivated
> 6 C-SPC => Mark activated
> 
> See how you're not getting "Mark set" any time after the first message?

Yes, technically, it doesn't set a mark, it just activates the
existing mark.  And the global-mark-ring section says that Emacs
pushes a mark on the ring when it sets the mark in some buffer.  Which
is not what happens here.

> Maybe a couple of sentences should be added to the manual regarding this behavior, because mark ring is
> often a source of confusion for the new users.

If you can tell what are the confusions, I could work on clarifying
them.