Looks good to me. I'm actually tempted to consider defaulting to uncompressed as a bug, and simply switch to compressing by default. (When I implemented this, I never even considered that uncompressed was the default for ZipFile).

@brettcannon what's your view on this? The only compatibility issue I can see would be for Pythons built without zlib support. Is that something we'd need to consider? And if so, would having an --uncompressed flag to request the old behaviour be sufficient?

The module needs to work with zlib not existing and it should default to uncompressed. I don't view adding a single boolean argument to a call burdensome if it makes people think about the trade-offs of compatibility and decompression overhead versus download/disk size.

OK, cool. Thanks for the clarification.

Thanks for the contribution, @zmwangx!

Thanks for the quick turnaround!