convert-ly can't cope with accented filename

[Nick Payne]

Try to run convert-ly on a file with an accented name and I get the 
following:

> convert-ly --edit "/home/nick/lilypond/Bésard_preludio.ly"
convert-ly (GNU LilyPond) 2.13.10
Traceback (most recent call last):
  File "/usr/local/lilypond/usr/bin/convert-ly", line 337, in ?
    main ()
  File "/usr/local/lilypond/usr/bin/convert-ly", line 331, in main
    do_one_file (f)
  File "/usr/local/lilypond/usr/bin/convert-ly", line 233, in do_one_file
    ly.stderr_write (_ ("Processing `%s\'... ") % infile_name)
  File 
"/usr/local/lilypond/usr/share/lilypond/current/python/lilylib.py", line 
59, in stderr_write
    encoded_write (sys.stderr, s)
  File 
"/usr/local/lilypond/usr/share/lilypond/current/python/lilylib.py", line 
51, in encoded_write
    f.write (s.encode (f.encoding or 'utf_8'))
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 33: 
ordinal not in range(128)

Save the same file to a different name without the accent and convert-ly 
is fine:

> convert-ly --edit "/home/nick/lilypond/Besard_preludio.ly"
convert-ly (GNU LilyPond) 2.13.10
Processing `/home/nick/lilypond/Besard_preludio.ly'...
Applying conversion: 2.13.10

Running LP 2.13.10 on x64 Ubuntu.

Nick