AFAIK list.lower() does not work: "AttributeError: 'list' object has no attribute 'lower'". 
So that would mean copying this loop into assembler.py, which then will be run on each call of rar_contains_unwanted_file()

I checked interface.py, but I see no calls from the main SABnzbd.py, so if I put it there, how does it get called?