bug#6447: 23.1; revert-buffer in *vc-diff*

[Tom Tromey <tromey@redhat.com>]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the bug-gnu-emacs@gnu.org mailing list,
and to the gnu.emacs.bug news group.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


I typed '=' in a *vc-dir* buffer to get a diff.
It would be nice if revert-buffer in the *vc-diff* buffer re-ran the
same diff command.


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/23.1/etc/DEBUG for instructions.


In GNU Emacs 23.1.1 (i386-redhat-linux-gnu, GTK+ Version 2.16.6)
 of 2010-04-01 on x86-01.phx2.fedoraproject.org
Windowing system distributor `The X.Org Foundation', version 11.0.10603901
configured using `configure  '--build=i386-redhat-linux-gnu' '--host=i386-redhat-linux-gnu' '--target=i586-redhat-linux-gnu' '--program-prefix=' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/var/lib' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--with-dbus' '--with-gif' '--with-jpeg' '--with-png' '--with-rsvg' '--with-tiff' '--with-xft' '--with-xpm' '--with-x-toolkit=gtk' 'build_alias=i386-redhat-linux-gnu' 'host_alias=i386-redhat-linux-gnu' 'target_alias=i586-redhat-linux-gnu' 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-bu
 ffer-size=4 -m32 -march=i586 -mtune=generic -fasynchronous-unwind-tables''

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

Major mode: Group

Minor modes in effect:
  shell-dirtrack-mode: t
  diff-auto-refine-mode: t
  erc-list-mode: t
  erc-menu-mode: t
  erc-autojoin-mode: t
  erc-ring-mode: t
  erc-pcomplete-mode: t
  erc-track-mode: t
  erc-track-minor-mode: t
  erc-match-mode: t
  erc-button-mode: t
  erc-fill-mode: t
  erc-stamp-mode: t
  erc-netsplit-mode: t
  erc-spelling-mode: t
  erc-truncate-mode: t
  gnus-undo-mode: t
  erc-status-mode: t
  erc-services-mode: t
  erc-networks-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-move-to-prompt-mode: t
  erc-readonly-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
u s t SPC b e c a u s e SPC m y SPC i m p r e s s i 
o n SPC i s SPC t h a t SPC m o s t SPC o f SPC t h 
e SPC g <backspace> t a r g e t SPC s t u f f SPC i 
s SPC r e a l l y SPC q u i t e SPC h o s t - i n d 
e p e n d e n t <return> b u t SPC I SPC h a v e SPC 
n o t SPC a c t u a l l y SPC t r i e s <backspace> 
d SPC s <backspace> a SPC b u i l d SPC o n SPC s o 
l a r i s , SPC s o SPC w h o SPC k n o w s <return> 
C-z n C-s SPC . SPC C-p C-p E E E C-u C-n E E S-SPC 
C-z o C-z o C-z o <f10> <f10> <f10> y e a h <return> 
a n y t h i n g SPC l i k e SPC t h a t SPC i s SPC 
p r <M-backspace> a SPC b u g , SPC b u t SPC o <M-backspace> 
I SPC r e a l i z e SPC t i m e SPC i s SPC l i m i 
t e d . . . <return> <f10> <f10> <f10> C-z n = E E 
S-SPC SPC = E E E S-SPC E E E q s C-u C-n C-n C-n SPC 
E q s M-x r e p o r t - e m <tab> b <tab> <return>

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Tom