bug#4219: 23.1; case insensitive + partial completions

[Eli Barzilay <eli@barzilay.org>]

Start with a default Emacs, and

  (setq read-file-name-completion-ignore-case t)
  (setq completion-styles '(partial-completion))

Now go to a directory that has two files called

  INSTALL
  install-sh

Hit `C-x C-f ins TAB' -- it will be completed to "insTALL".


In GNU Emacs 23.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.10.14)
 of 2009-08-01 on winooski.ccs.neu.edu
Windowing system distributor `The X.Org Foundation', version 11.0.10300000
configured using `configure  '--prefix=/home/eli/bin/local/emacs-dir''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: POSIX
  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
  value of $XMODIFIERS: nil
  locale-coding-system: iso-latin-1-unix
  default-enable-multibyte-characters: t

Major mode: Dired by name

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t