bug#12547: 23.3; sh-mode backward-list with case and =

[Jack Duthen <duthen.mac.01@gmail.com>]

--text follows this line--
This bug report will be sent to the Free Software Foundation,
not to your local site managers!
Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

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

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug.  If you can, give
a recipe starting from `emacs -Q':

Create ans edit the file "bug_file.ksh".
Try C-M-n and C-M-p over the file:
=> Unbalanced parentheses

$ cat bug_file.ksh
#!/bin/ksh

# Move point here and type C-n C-M-n C-M-n C-M-n

function foo_ok {
    case "${foo}" in
        (=G*) ;;
    esac
}

function foo_ok {
    case "${foo}" in
        "=G"*) ;;
    esac
}

function foo_bug {
    case "${foo}" in
        =G*) ;;
    esac
}

# Move point here and type C-p C-M-p
# bug_file.ksh ends here



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'.
For information about debugging Emacs, please read the file
/usr/share/emacs/23.3/etc/DEBUG.


In GNU Emacs 23.3.1 (i686-pc-linux-gnu, GTK+ Version 2.24.10)
 of 2012-09-21 on akateko, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11103000
configured using `configure  '--build' 'i686-linux-gnu' '--build'
'i686-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/23.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.3/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.3/leim'
'--with-crt-dir=/usr/lib/i386-linux-gnu' '--with-x=yes'
'--with-x-toolkit=gtk' '--with-toolkit-scroll-bars'
'build_alias=i686-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g'
'CPPFLAGS=-D_FORTIFY_SOURCE=2''

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: Shell-script

Minor modes in effect:
  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-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> C-x C-f . e <tab> J <tab> B <tab> <backspace>
E <tab> B <tab> B <tab> <tab> K <tab> <tab> <return>
C-n C-n C-M-n C-M-n C-M-n <help-echo> <help-echo> <help-echo>
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo>
<help-echo> <help-echo> <menu-bar> <help-menu> <se
nd-emacs-bug-report>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Making completion list...
Setting up indent for shell type pdksh
setting up indent stuff
Indentation variables are now local.
Indentation setup for shell type pdksh
forward-list: Scan error: "Unbalanced parentheses", 265, 1

Load-path shadows:
/usr/share/emacs/23.3/site-lisp/debian-startup hides
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/23.3/site-lisp/dictionaries-common/flyspell hides
/usr/share/emacs/23.3/lisp/textmodes/flyspell
/usr/share/emacs/23.3/site-lisp/dictionaries-common/ispell hides
/usr/share/emacs/23.3/lisp/textmodes/ispell

Features:
(shadow sort mail-extr message sendmail ecomplete rfc822 mml mml-sec
password-cache mm-decode mm-bodies mm-encode mailcap mail-parse rfc2231
rfc2047 rfc2045 qp ietf-drums mailabbrev nnheader gnus-util netrc
time-date mm-util mail-prsvr gmm-utils wid-edit mailheader canlock sha1
hex-util hashcash mail-utils emacsbug regexp-opt sh-script executable
help-mode easymenu view tooltip ediff-hook vc-hooks lisp-float-type
mwheel x-win x-dnd font-setting tool-bar dnd fontset image fringe
lisp-mode register page menu-bar rfn-eshadow timer select scroll-bar
mldrag 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 loaddefs button minibuffer faces cus-face files text-properties
overlay md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
system-font-setting font-render-setting gtk x-toolkit x multi-tty emacs)