Now open that file with emacs -Q and run 'M-x diff-fixup-modifs'. It chokes because there's no , after the -1.
If I'm reading diff-mode.el correctly, the line that raises the error will *always* raise that error, because it's trying to use (match-end 2) as a character position after (match-string 2) has already returned
nil. Oops. :-/
In case it matters, my version of diff is:
$ diff --version diff (GNU diffutils) 3.0 Copyright (C) 2010 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
Written by Paul Eggert, Mike Haertel, David Hayes, Richard Stallman, and Len Tower.
In GNU Emacs 23.3.1 (i486-pc-linux-gnu, X toolkit, Xaw3d scroll bars) of 2011-04-10 on raven, modified by Debian Windowing system distributor `The X.Org Foundation', version 11.0.10905000 configured using `configure '--build' 'i486-linux-gnu' '--build' '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/23.3/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-x=yes' '--with-x-toolkit=lucid' '--with-toolkit-scroll-bars' '--without-gconf' 'build_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''
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: Diff
Minor modes in effect: diff-auto-refine-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-encryption-mode: t
auto-compression-mode: t line-number-mode: t transient-mark-mode: t
Recent input: <help-echo> <help-echo> <help-echo> M-x d i f <tab> SPC f i <tab> x <tab> <return> <help-echo> M-x r e
p o r <tab> <return>
Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Loading vc-git...done Making completion list... call-interactively: Wrong type argument: integer-or-marker-p, nil