bug#21982: 25.1.50; Building emacs-25 branch fails

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Cc: 21982@debbugs.gnu.org
> Date: Mon, 23 Nov 2015 21:35:50 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > If the abort is reproducible, by all means please do, and thanks.
> 
> git bisect says that:
> 
> --8<---------------cut here---------------start------------->8---
> c210b8b128c17929dbb8e0b0564ee25930d44dd1 is the first bad commit
> commit c210b8b128c17929dbb8e0b0564ee25930d44dd1
> Author: Juanma Barranquero <lekktu@gmail.com>
> Date:   Thu Nov 19 21:32:43 2015 +0100
>     Discover repository version in linked worktrees (bug#21930)
>     
>     * lisp/version.el (emacs-repository--version-git-1): Do not assume
>     HEAD is at .git/HEAD, it can also be at .git/worktrees/<branch>/HEAD.
>     (emacs-repository-get-version): Grok linked worktrees when EXTERNAL
>     is nil too.
> --8<---------------cut here---------------end--------------->8---
> 
> I verified that it is indeed bad and that the parent commit is good,
> whereby "good" means it builds successfully and "bad" means building
> fails.
> 
> Does that help?

Well, sort of.  Granted, no Lisp change can ever cause thrashing of
the malloc arena, so the above could only expose a bug that was
already there.

Was your branch tree created by "git worktree"?