Here's another bug report that talks about a 2GB file limit:
http://bugs.python.org/issue1189216
The diff offered there does not solve the problem; actually it's
possible that the diff may not have anything to do with fixing the
problem (though I'm not certain), but may just be a readability change.

I tried to program a solution based on other stuff I saw/read on the
internet, but ran into different problems....

I took the line:
bytes = self.fp.read(zinfo.compress_size)
and made it read a little bit at a time and add the result to bytes as
it went along.  This was really slow (as it had to add the result to the
larger and larger bytes string each time); I tried with a list, but I
couldn't find how to join the list back together into a string when done
(similar to the javascript join() method).  However, even with the list
method, I ran into an odd "memory error," as it looped through into the
higher numbers, that I have no idea why it was happening, so I gave up
at that point.

Also, I have no idea if this one line in the zipfile module is the only
problem or if there are others that will pop up once you get that part
fixed.