Python3.5: Fixup usage of difflib for its changes.
Python3.5: Fixup usage of difflib for its changes.

* The dates can no longer be None, so use the default value "" instead.

tempbottle/Nuitka,wfxiang08/Nuitka,wfxiang08/Nuitka,kayhayen/Nuitka,wfxiang08/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka,tempbottle/Nuitka,tempbottle/Nuitka,kayhayen/Nuitka,wfxiang08/Nuitka,tempbottle/Nuitka