changing a doc using the admin view fails

If you create a new document in the admin and upload it to document cloud then attempt to change the document in the admin view by uploading a NEW document, an error is thrown:

cannont find function getsize

even though the import exists.  It's possible the import needs to be added inside the function 

admin.py...
def save_model(...):
     from documentcloud.MultipartPostHandler import getsize
