Comment 6 for bug 266332

The thing I missed in trying to duplicate is the fact that
the exception is thrown in decode_rfc2231(). Thus, the
problem only occurs with a RFC2231 encoded header, i.e., one
with a long filename split into pieces as
   filename*0="first part of name containing ' character"
   filename*1="second part of name - etc."

The underlying problem is in the Python email library in
email/Utils.py.

See
http://mail.python.org/pipermail/email-sig/2006-July/000293.html
for a more complete description and a potential fix.