Another reason to not compress Python eggs is that the contents of the zip archives introduce non-determinism through their timestamps.
You can see it in action: $ git checkout fe17fb4a2c897fd9186f91887f5af63dd00d227a $ ./pre-inst-env guix build --rounds=2 acme If you save the output between rounds, you can use diffoscope to confirm that the differences between the rounds are the timestamps of the contents of the eggs.
