bug#24640: Crashes in 25.1

[Eli Zaretskii]

> From: Reuben Thomas <rrt@sc3d.org>
> Date: Tue, 11 Oct 2016 16:41:17 +0100
> Cc: 24640@debbugs.gnu.org
> 
>  Is it possible to disable this loading of undo-tree history? If so,
>  can you disable it and see if Emacs no longer crashes? If the crashes
>  stop when undo-tree history is not loaded, we will have to look
>  closely at what that loading does, because the problem is probably
>  there. The internals of undo changed in Emacs 25.
> 
> ​Yes, the crashes appear to stop when I comment out (global-undo-tree-mode) 
> in vars.el.

OK, so we have our prime suspect.  Can you tell where I can find the
exact version of undo-tree-mode you are using?

Phillip, could you please look into that package and see if you can
spot any potential problems with the Emacs 25 undo internals?  TIA.