bug#18878: 24.3; (setq rmail-nonignored-headers nil) causes rmail-copy-headers to error

[Dale R. Worley]

1. Create a mailbox file containing one message.  (I believe that any
mailbox file (containing at least one message) will suffice.)

2. Execute (setq rmail-nonignored-headers nil).

This has the defined meaning that there are no "nonignored" headers that
are displayed even if they match rmail-ignored-headers:

    rmail-nonignored-headers is a variable defined in `rmail.el'.
    Its value is "^x-spam-status:"

    Documentation:
    Regexp to match X header fields that Rmail should show.
    This regexp overrides `rmail-ignored-headers'; if both this regexp
    and that one match a certain header field, Rmail shows the field.
    If this is nil, ignore all header fields in `rmail-ignored-headers'.

3. Run Rmail on the mailbox file:  C-u M-x rmail RET ...file-name... RET.

4. An error message is displayed in the minibuffer.  As it is recorded
in the *Messages* buffer:

    rmail-copy-headers: Wrong type argument: stringp, nil

5. Setting debug-on-error to t before step 3 will give a traceback
showing that rmail-copy-headers has used the value of
rmail-nonignored-headers as an argument to looking-at without first
checking whether the value of rmail-nonignored-headers is non-nil.




In GNU Emacs 24.3.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.8.2)
 of 2013-08-14 on buildvm-15.phx2.fedoraproject.org
Windowing system distributor `Fedora Project', version 11.0.11404000
System Description:     Fedora release 19 (Schrödinger’s Cat)

Configured using:
 `configure '--build=x86_64-redhat-linux-gnu'
 '--host=x86_64-redhat-linux-gnu' '--program-prefix='
 '--disable-dependency-tracking' '--prefix=/usr' '--exec-prefix=/usr'
 '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc'
 '--datadir=/usr/share' '--includedir=/usr/include'
 '--libdir=/usr/lib64' '--libexecdir=/usr/libexec'
 '--localstatedir=/var' '--sharedstatedir=/var/lib'
 '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--with-dbus'
 '--with-gif' '--with-jpeg' '--with-png' '--with-rsvg' '--with-tiff'
 '--with-xft' '--with-xpm' '--with-x-toolkit=gtk3' '--with-gpm=no'
 'build_alias=x86_64-redhat-linux-gnu'
 'host_alias=x86_64-redhat-linux-gnu' 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g
 -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
 --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic'
 'LDFLAGS=-Wl,-z,relro ''

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

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-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> M-x r e p o r t - e m a c s - b u g <r
eturn>

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 mail-prsvr mail-utils time-date tooltip ediff-hook vc-hooks
lisp-float-type mwheel x-win x-dnd 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 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 dbusbind dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)

-- 
--
Dale WORLEY                                             worley@alum.mit.edu