Intuitively I would expect the output to be:

    $ cat base.txt
    -r base.txt
    pytz==* (glob)
    six==* (glob)
    times==* (glob)
    
    $ cat base.txt
    python-dateutil==* (glob)

Have you considered that approach? I'm not saying one is better than the other, but I'm trying to compare the two and see what would make most sense.