bug#22229: Error when running script from directory with non-ASCII characters

[Vicente Vera <vicentemvp@gmail.com>]

Guile chokes when running a .scm script from a directory with
non-ASCII characters.

A simple test script:

-------------------
#!/usr/bin/guile -s
!#
;; coding: utf-8
(display "hey")
(newline)
-------------------

$ cd ~/código/
$ ./test.scm
;;; Stat of /home/me/c??digo/./test.scm failed:
;;; ERROR: In procedure stat: No such file or directory:
"/home/me/c??digo/./test.scm"
Backtrace:
In ice-9/boot-9.scm:
 157: 8 [catch #t #<catch-closure 9949e00> ...]
In unknown file:
   ?: 7 [apply-smob/1 #<catch-closure 9949e00>]
In ice-9/boot-9.scm:
  63: 6 [call-with-prompt prompt0 ...]
In ice-9/eval.scm:
 432: 5 [eval # #]
In ice-9/boot-9.scm:
2401: 4 [save-module-excursion #<procedure 9957cc0 at
ice-9/boot-9.scm:4045:3 ()>]
4052: 3 [#<procedure 9957cc0 at ice-9/boot-9.scm:4045:3 ()>]
1724: 2 [%start-stack load-stack ...]
1729: 1 [#<procedure 995e738 ()>]
In unknown file:
   ?: 0 [primitive-load "/home/me/c??digo/./test.scm"]

ERROR: In procedure primitive-load:
ERROR: In procedure open-file: No such file or directory:
"/home/me/c??digo/./test.scm"

When removing the UTF-8 character from the working directory Guile
runs as expected:

$ cd ~
$ mv -T código/ code/
$ cd code/
$ ./test.scm
hey

Locale: en_US.UTF-8

System: Linux 3.16.0-4-686-pae #1 SMP Debian 3.16.7-ckt20-1+deb8u1
(2015-12-14) i686 GNU/Linux

Guile version:
$ guile -v
guile (GNU Guile) 2.0.11
Packaged by Debian (2.0.11-deb+1-9)
...