->study() loops

I have a program that goes through the attachments of a message and
attempts to get the content type with

if (defined($type = $attachment->study("Content-Type")))

The code has worked fine, but a message came in today that causes study()
to go into an infinite loop.  I just installed the latest version from
CPAN, and it still loops.  Hopefully, I'm not doing something silly.  I
have made the offending message available at

http://www.cune.org/Russell.Mosemann/msg.txt

If you would have a moment to take a look at it, that would be great.  
Thank you very much.

----
Russell Mosemann, Ph.D. * Computing Services * Concordia University, Nebraska
"The tomato, by law, is a vegetable.  By nature it is a fruit."