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