plpythonu and bytea

Hey, I'm trying to write some plpython procedures that read binary data from
images on the disk and store it in bytea fields. I'm basically trying to
write a plpython procedure that accepts a varchar and returns a bytea, with
these procedure contents:

data = file(args[0]).read()
return data

(The actual procedure will have more in it, but that's the tricky part). But
the returned data is always severely truncated. Is returning a bytea from
plpython impossible, or is there some way I should escape the data string?
I've tried using the built in encode and decode functions, but they don't
seem to help. If worse comes to worse, I can store the base64 encoded
version, of course, but I'd rather not do that. Any ideas?

Greg