The `shell-command' function fails if `w32-downcase-file-names' is true.


Recipe from -Q:
M-: (setq SPC w32-downcase-file-names SPC t) RET

M-! dir <return>


Result:
(Shell command failed with error)
shell-command-on-region: File exists: c:/users/buster/appdata/local/temp/emxxxxxx


In GNU Emacs 24.3.50.1 (i386-mingw-nt6.2.9200)
 of 2013-02-08 on MACHINE
Bzr revision: 111700 monnier@iro.umontreal.ca-20130208174209-vpjpdh4qipaceoh5
Windowing system distributor `Microsoft Corp.', version 6.2.9200
Configured using:
 `configure --with-gcc (4.7) --cflags -I c:/gnuwin32/include --ldflags
 -L c:/gnuwin32/lib’


Important settings:
  value of $LANG: ENG
  locale-coding-system: cp1252
  default enable-multibyte-characters: t


Major mode: Lisp Interaction


Minor modes in effect:
  shell-dirtrack-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t


Recent input:
( s e t q SPC w 3 2 - d o w n c a s e - f i l e - n 
a m e s SPC t ) C-x C-e M-! g c c SPC - - v e r s i 
o n <return> M-x r e p o r t - e m a c s w - b u g
<return>


Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
t
(Shell command failed with error)
shell-command-on-region: File exists: c:/users/buster/appdata/local/temp/emxxxxxx


Load-path shadows:
None found.


Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils shell pcomplete comint ansi-color ring
time-date tooltip ediff-hook vc-hooks lisp-float-type mwheel dos-w32
ls-lisp w32-common-fns disp-table w32-win w32-vars tool-bar dnd fontset
image regexp-opt fringe tabulated-list newcomment lisp-mode register
page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core frame cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew
greek romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer button
faces cus-face macroexp files text-properties overlay sha1 md5 base64
format env code-pages mule custom widget hashtable-print-readable
backquote make-network-process w32notify w32 multi-tty emacs)