bug#28412: 26.0.50; Let save-some-buffers accept write-contents-functions

[Eli Zaretskii]

> From: Kaushal Modi <kaushal.modi@gmail.com>
> Date: Mon, 18 Sep 2017 21:48:15 +0000
> Cc: Eli Zaretskii <eliz@gnu.org>, 28412@debbugs.gnu.org
> 
> Yup. I also see this in the "(emacs) Undo" Info node:
> 
> Some specialized buffers do not make undo records. Buffers whose
> names start with spaces never do; these buffers are used internally by
> Emacs to hold text that users don’t normally look at or edit.
> 
> But I cannot find the code that implements that.

It's in get-buffer-create:

  bset_undo_list (b, SREF (name, 0) != ' ' ? Qnil : Qt);