Last record in file doesn't write to newline

[deanhystad]

From the difflib documentation:

compare(a, b)
Compare two sequences of lines, and generate the delta (a sequence of lines).

Each sequence must contain individual single-line strings ending with newlines. Such sequences can be obtained from the readlines() method of file-like objects. The delta generated also consists of newline-terminated strings, ready to be printed as-is via the writelines() method of a file-like object.

It may be slightly inconvenient, but at least it tells you up front.