I'm trying to use your library. Here's a simple example of how I'm trying it:

 b1 = open('b1.bin', 'rb').read()
 b2 = open('b2.bin', 'rb').read()
 d = xdelta3.encode(b1, b2)
 b3 = xdelta3.decode(b1, d)
 print(b2 == b3)

This gives me an exception: xdelta3.XDeltaError: Output of decoding delta longer than expected

I'm attaching a zip file with b1.bin and b2.bin. By the way, they're simple HTML files, I just made sure to treat them as binary so I don't trip over encodings. Also, when trying it in reverse (not b1 -> b2, but b2 -> b1) it all works well.

$ python --version
Python 3.6.1
Running on Mac OS, Python installed via pyenv. xdelta3==0.0.5.

files.zip