smtpmail-auth-credentials saves password even when 'password' is nil

[Justus Piater]

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In GNU Emacs 21.4.1 (i486-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2005-10-03 on trouble, modified by Debian
configured using `configure '--build=i486-linux-gnu' '--host=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' '--with-x=yes' 
'--with-x-toolkit=athena' 'CFLAGS=-DDEBIAN -g -O2' 'build_alias=i486-linux-gnu' 
'host_alias=i486-linux-gnu''
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
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

I use smtpmail.el from CVS (Revision 1.84 I believe) with STARTTLS
authentification. I do not want passwords to appear in my .emacs;
therefore, in the customizable variable smtpmail-auth-credentials, I
set 'password' to 'nil' ("query when needed"). This works as expected,
except that this password magically shows up in my .emacs after some
time. This is what I believe is happening:

Any customization replaces the entire variable custom-set-variables in
.emacs. If emacs knows about my SMTP password because I have typed it
into the minibuffer to send some email, any subsequent customization
of any customizable Emacs variable saves this password to
smtpmail-auth-credentials.

Thanks,
Justus


Recent input:
l i b <tab> <M-backspace> e m <tab> <tab> a <tab> <tab> 
/ <tab> <tab> 2 <tab> l i s <tab> s m <tab> <M-backspace> 
<M-backspace> <M-backspace> m a <tab> i <tab> s m <tab> 
C-g M-x l o c C-g C-x b * <backspace> <return> C-x 
C-f s h <tab> e m <tab> l i s <tab> s m <tab> <return> 
<down-mouse-5> <mouse-5> <double-down-mouse-5> <double-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> C-s b u g C-s 
C-s C-s C-s C-s C-s C-s C-s C-s C-s C-s C-s M-< <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<menu-bar> <help-menu> <report-emacs-bug>

Recent messages:
Auto-saving...done
Library is file /home/piater/share/emacs/lisp/smtpmail.el
isearch-abort: Quit
Loading ange-ftp...done
Making completion list... [4 times]
Quit
call-interactively: Quit
Mark saved where search started
Mark set
Loading emacsbug...done

-- 
Justus H. Piater, Ph.D.         http://www.montefiore.ulg.ac.be/~piater/
Institut Montefiore, B28        Phone: +32-4-366-2279
Université de Liège, Belgium    Fax:   +32-4-366-2620