start-process normalizes the given PROGRAM path by destructively modifying its contents.

This is problematic if the path variable is reused later on.

Minimal repro:

(let ((path "c:/Windows/System32/clip.exe"))

  (start-process "" nil path)

  path) ; => "c:\\Windows\\System32\\clip.exe"

In GNU Emacs 24.5.1 (i686-pc-mingw32)

 of 2015-04-11 on LEG570

Windowing system distributor `Microsoft Corp.', version 6.3.9600

Configured using:

 `configure --prefix=/c/usr --host=i686-pc-mingw32'

Important settings:

  value of $LANG: DEU

  locale-coding-system: cp1252

Major mode: Lisp Interaction

Minor modes in effect:

  tooltip-mode: t

  electric-indent-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 messages:

For information about GNU Emacs and the GNU system, type C-h C-a.

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 help-fns mail-prsvr mail-utils time-date tooltip electric

uniquify 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 prog-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 nadvice

loaddefs 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)

Memory information:

((conses 8 73857 5808)

 (symbols 32 17432 0)

 (miscs 32 33 131)

 (strings 16 10612 4319)

 (string-bytes 1 268415)

 (vectors 8 9520)

 (vector-slots 4 383153 5554)

 (floats 8 57 68)

 (intervals 28 196 45)

 (buffers 508 11))