title: rdiff python module
body: <p>Is there a python module that has the functionality for computing rdiff signatures and delta differencing?</p>
  
  <p>I need to perform these operations on a cross-platform application so I'll need something that will bundle into py2exe, py2app etc.</p>
  
  <p>I've done a bunch of searching but I can't seem to get anything working. Pysync, rdiff-backup, librsync all come up but I've not been able to get anything working inside of python. </p>