I don't see a problem here. Your first file has more lines, so it produces more output than the second file. Presumably the difference in output you see when you run your program is a result of this. But since we can't see the code, we can't know for sure.

I don't see anything to make me think this is related to what version of Windows your program is running under, or that there's a bug in python. So I'm going to close this issue. If you can produce a program that demonstrates a bug in python, you can provide more details (including the full source code) and re-open this issue.

I suggest you look for help on the python-list mailing list: https://mail.python.org/mailman/listinfo/python-list