bug#4987: 23.1; shell-command: optionally include working dir in prompt

[trentbuck]

At http://namazu.org/~tsuchiya/elisp/shell-command.el is an emacs
library that "enables tab-completion for `shell-command'".

I noticed recently that Emacs does this internally now.  Yay!  But one
thing shell-command.el did that Emacs 23 doesn't appear to do, is to
include the working directory in the shell-command and
dired-do-shell-command prompts.  It'd be neat if Emacs did that, too.

In GNU Emacs 23.1.1 (i486-pc-linux-gnu)
 of 2009-09-14 on raven, modified by Debian
configured using `configure  '--build=i486-linux-gnu' '--host=i486-linux-gnu' 
'--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' 
'--localstatedir=/var/lib' '--infodir=/usr/share/info' 
'--mandir=/usr/share/man' '--with-pop=yes' 
'--enable-locallisppath=/etc/emacs23:/etc/emacs:/usr/local/share/emacs/23.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.1/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.1/leim'
 '--with-x=no' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 
'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  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_AU.utf8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: rcirc

Minor modes in effect:
  shell-dirtrack-mode: t
  diff-auto-refine-mode: t
  rcirc-track-minor-mode: t
  xterm-mouse-mode: t
  savehist-mode: t
  icomplete-mode: t
  partial-completion-mode: t
  show-paren-mode: t
  delete-selection-mode: t
  use-hard-newlines: 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
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
ESC O B ESC O B ESC O B ESC O B ESC ! C-g ESC O A ESC 
O A ESC O A ESC O A ESC O A ESC O A ESC O A ESC O A 
ESC O A ESC O A ESC O A ESC O A ESC O A ESC O A ESC 
! C-g ESC ! C-g ESC ! C-g C-x ESC O C ESC O B C-x ESC 
O B Y o u ' d SPC t h i n k SPC t h e r e ' s SPC b 
e SPC a SPC w a y SPC t o SPC g o SPC b a c k SPC r 
DEL f r m SPC DEL DEL o m SPC a SPC s c r e e n l o 
g SPC t o SPC t p u t SPC c a l l s ESC b ESC b ESC 
f ( 1 ) C-e , SPC g i v e n SPC t h e SPC T E R M SPC 
t y p e RET C-x ESC O D C-x ESC O C C-x ESC O B ESC 
x r e p o r t b u g DEL DEL DEL SPC e m a c s - b u 
g C-g C-x ESC O D ESC x f i SPC l i b RET s h e l l 
- c o m m a n d RET C-x d C-g ESC < C-@ ESC O B ESC 
O B ESC O B ESC w C-x ESC O C C-x ESC O B ESC x r e 
p o r t SPC e m a c s SPC b u g RET C-g ESC x ESC O 
A RET

Recent messages:
Saving file /home/twb/Preferences/.emacs...
Wrote /home/twb/Preferences/.emacs
Quit
Mark set
Saving file /home/twb/Preferences/.emacs...
Wrote /home/twb/Preferences/.emacs
(No changes need to be saved)
Quit [6 times]
Mark set
Mark activated
Quit