bug#13557: 24.3.50; auto-revert-use-notify t always reverts buffers after save

[Dmitry Gutov <dgutov@yandex.ru>]

Whenever I save a buffer, if (and only if) auto-revert-use-notify is t,
auto-revert-mode "reverts" it in a second or two, usually eating
buffer-undo-list in the process.

Latest trunk, local (ext4) filesystem in a VM, easily reproduces from emacs -Q.

In GNU Emacs 24.3.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.6.0)
 of 2013-01-26 on vbx
Bzr revision: 111607 acm@muc.de-20130125181814-v129xa7rwqbntgq1
Windowing system distributor `The X.Org Foundation', version 11.0.11300000
System Description:	Ubuntu 12.10

Important settings:
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Emacs-Lisp

Minor modes in effect:
  recentf-mode: t
  paredit-mode: t
  elisp-slime-nav-mode: t
  whitespace-mode: t
  global-undo-tree-mode: t
  undo-tree-mode: t
  global-diff-hl-mode: t
  diff-hl-mode: t
  diff-auto-refine-mode: t
  savehist-mode: t
  yas-global-mode: t
  yas-minor-mode: t
  ido-ubiquitous-mode: t
  ido-everywhere: t
  show-paren-mode: t
  global-auto-revert-mode: t
  autopair-global-mode: t
  cua-mode: t
  winner-mode: t
  global-rinari-mode: t
  global-company-mode: t
  company-mode: t
  eproject-mode: t
  eldoc-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  auto-fill-function: do-auto-fill
  transient-mark-mode: t

Recent input:
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down-mouse-1> <mouse-1> 
<down-mouse-1> <mouse-1> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<down-mouse-1> <mouse-1> <down> <down> <down> <down> 
<down> <down> <down> <down-mouse-1> <mouse-1> C-x C-e 
<down-mouse-1> <mouse-1> C-x C-e <down-mouse-1> <mouse-1> 
<help-echo> <down-mouse-1> <mouse-1> <help-echo> <help-echo> 
<help-echo> <help-echo> : 9 s e t q SPC C-x C-s C-z 
C-z C-S-z C-z C-z C-z <end> a s d C-z C-a C-g C-x C-s 
a s d a s C-x C-s C-z C-z <C-backspace> C-x C-s <backspace> 
C-x C-s <down> <down> M-: ( s e t q SPC a u t o - r 
e v e r t - u s e - n o t i f y SPC n i l <backspace> 
<backspace> <backspace> C-x <up> C-x <right> <up> <up> 
<up> <down> <down> <down> <down> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> C-x C-e <left> C-x <down> n i l <end> 
<return> <return> C-x C-s <backspace> C-x C-s <help-echo> 
<down-mouse-1> <mouse-1> C-h v m o d i f i c a t i 
o n s <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> u n 
d o - l i <right> <right> <right> <return> <next> <prior> 
<prior> q <down-mouse-1> <mouse-1> <help-echo> <down-mouse-1> 
<mouse-1> <return> C-x C-s M-: <up> <end> <left> <backspace> 
<backspace> <backspace> t <return> <backspace> C-x 
C-s C-x <right> M-x r e p o r t <return>