bug#30182: Update

[Eli Zaretskii]

> Date: Tue, 23 Jan 2018 19:25:42 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 30182@debbugs.gnu.org
> 
> So here's the thing: timer-list has 5 elements, but concat thinks
> there are only 4 elements, so it starts with a 4-element list, and
> then there's no place there to put the 5th element, which happens to
> be the savehist-autosave timer.

A couple more suggestions for investigating things:

 . Could the problem be caused by mode-line-default-help-echo being a
   function now, not just a string?  Maybe try to revert only that
   portion of the changeset, and see if that helps.

 . Related: could it be that mode-line-default-help-echo signals an
   error?  Try running the reproducing recipe with a breakpoint in
   safe_eval_handler.  If that breakpoint breaks, show the backtrace,
   and use "pp" to show the values of arg and args[].