incorrectly rendered unicode (korean) character in ps (fonttype=3) and pdf backend

A slightly different (and can be minor) issue related with unicode
support in ps backend.
For one of my Korean font, it raises an following exception.

File "/users/research/lee/local/lib/python2.5/site-packages/matplotlib/backends/backend_ps.py",
line 688, in draw_unicode
   self.set_font(font.get_sfnt()[(1,0,0,6)], prop.get_size_in_points())
KeyError: (1, 0, 0, 6)

Apparently, the return value of get_sfnt() for this particular font
does not have (1,0,0,6) key.

Agg, png, and Cairo backends are all okay with this font.

Anyhow, as it happens for only one font AFAIK, and as we can use Cairo
backend instead, there may not be much need to fix this unless it can
be easily done.

Regards,

-JJ