bug#76123: [PATCH] Eliminate savehist duplicated symbols

[Eli Zaretskii]

> Cc: 76123@debbugs.gnu.org
> From: Ship Mints <shipmints@gmail.com>
> Date: Fri, 7 Feb 2025 19:04:27 -0500
> 
> Revised patch attached with two tests to get savehist tests started. One is a 
> basic functions test and the
> other a duplicate test. They probably could be combined into one test, tbh, 
> but not precisely sure what the
> Emacs Core testing regime is for functionality.
> 
> I tested on both Emacs 29 with the duplicate issue and with the duplicate 
> avoidance patch applied.

Thanks.  There's one more nit: I think this change needs to be called
out in NEWS.  It changes user-facing behavior, so users should be
informed about that.