the behavior of compare and patch file of the same?

[fwang2]

If two files are the same content, applying the following procedure will fail ... diff mytest.1.txt and mytest3.txt will differ. Is this the intended behavior, or am I missing something.

#!/usr/bin/python

import librsync

with open("mytest1.txt", "wb") as f:
    f.write("hello world\n")

with open("mytest2.txt", "wb") as f:
    f.write("hello world\n")

with file("mytest1.txt", "rb") as src, file("mytest2.txt", "rb") as dest, \
    file("mytest3.txt", "wb") as patched:

    signature = librsync.signature(dest)
    delta = librsync.delta(src, signature)
    librsync.patch(dest, delta, patched)