bug#13262: 24.3.50; crash when multibyte directory name completion.

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Mon, 24 Dec 2012 00:10:41 -0500
> Cc: 13262@debbugs.gnu.org
> 
> > GNU Emacs 24.3.50.1 (i386-mingw-nt6.1.7601)
> 
> Thanks.  Can you reproduce this in the current pretest (24.2.91)?

Yes, he could, until revision 111077 on the emacs-24 branch fixed that
(I think).

Sorry, the changes touch quite a few places, but they all had the same
problem: unwarranted assumptions that input Lisp strings passed to
primitives are multibyte.  The crash happened because file completion
calls directory-file-name with a unibyte string (an encoded file
name).  A similar mess was found and fixed in file-name-directory and
in expand-file-name.