0408204 Fix the way how KojiContentGenerator computes filesize.

Authored and Committed by jkaluza 5 years ago
    Fix the way how KojiContentGenerator computes filesize.
    
    The current code reads the data, converts them to unicode string and
    then uses the `len()` of that string as filesize. This is wrong,
    because Koji expects filesize to be really number of bytes, not number
    of characters.
    
    Therefore, in this commit, the filesize is computed from raw data (bytes).