bug#5280: read-file-name return wrong dir if partial-completion-mode enabled

[Oleksandr Gavenko]

This happen with Emacs 22.3.1 from
http://ftp.gnu.org/pub/gnu/emacs/windows/emacs-22.3-bin-i386.zip

With 23.1 http://ftp.gnu.org/pub/gnu/emacs/windows/ such error not
occured. On Emacs 21.4 function read-file-name not defined.

STEP #1.

  > cd test
  > mkdir dir-1xxx dir-1yyy .svn
  > edit bug.el  --- I put here:

(read-file-name "Enter file" default-directory default-directory t nil 
'file-directory-p)
(partial-completion-mode t)

  > runemacs --no-init-file --no-site-file --debug-init

STEP #2.
Next C-x C-f d:/tmp/test/bug.el RET,
execute read-file-name by C-x C-e, in prompt just type RET, got 
"d:/tmp/test/" - OK.

STEP #3.
execute (partial-completion-mode t)
and repeat executing (read-file-name  ...), got "d:/tmp/test/dir-1" - ERROR.

If do not create .svn dir (which in list completion-ignored-extensions)
on step #1 we got correct value on step #3.
Also correct work if remove ".svn" from completion-ignored-extensions
and partial-completion-mode enabled.

--
Best regards!