default-case-fold-search vs html coding system

[Kevin Ryde <user42@zip.com.au>]

If default-case-fold-search is set to nil, the coding system detection
for html fails on various files.  For example,

	wget http://www.gnu.org/home.de.html
	emacs -Q
	M-x customize-variable case-fold-search
	click toggle
	click save for current session
	C-x C-f home.de.html
	C-h C Ret
	=> undecided-unix

where I hoped to get "utf-8" which is in the meta tag, and which you get
if case-fold-search is t.

I guess sgml-html-meta-auto-coding-function may have to let bind
case-fold-search to ensure variations of "DOCTYPE", "Content-Type", etc,
are matched.

I wondered if something similar could apply to xml files in
sgml-xml-auto-coding-function on "<?xml", but I don't know what the
standards say about that tag.  (If it's always lower case then it might
be worth thinking about binding case-fold-search to nil so as not to do
different things according to the user's default.)


In GNU Emacs 22.1.1 (i486-pc-linux-gnu, GTK+ Version 2.10.13)
 of 2007-07-07 on raven, 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' '--enable-locallisppath=/etc/emacs22:/etc/emacs:/usr/local/share/emacs/22.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/22.1/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/22.1/leim' '--with-x=yes' '--with-x-toolkit=gtk' '--with-toolkit-scroll-bars' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2''

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_AU
  locale-coding-system: iso-8859-1
  default-enable-multibyte-characters: t