I agree it's a problem without an easy solution. It's not just a problem with python, it's exactly the same thing with rubygems (where it's been getting similar discussion, especially after a rubygems vulnerability a few months ago).
But: The elephant in the room when talking about package signing is what exactly we are trusting.
I think it's actually relatively clear. When I install "rails", I want to know that it really did come from the "rails team", and not from a third party man in the middle.
That's the most that can be expected, and that's sufficient. There's no way to technologically ensure that the rails team itself isn't intentionally including malware in their release. And of course no way to technologically ensure that the release doesn't have bugs or vulnerabilities.
The goal is just ensuring the release is really from who it says it's from. Which is of course hard enough already, for the reasons dealt with in OP, and because who is "the rails team" exactly anyway?
But: The elephant in the room when talking about package signing is what exactly we are trusting.
I think it's actually relatively clear. When I install "rails", I want to know that it really did come from the "rails team", and not from a third party man in the middle.
That's the most that can be expected, and that's sufficient. There's no way to technologically ensure that the rails team itself isn't intentionally including malware in their release. And of course no way to technologically ensure that the release doesn't have bugs or vulnerabilities.
The goal is just ensuring the release is really from who it says it's from. Which is of course hard enough already, for the reasons dealt with in OP, and because who is "the rails team" exactly anyway?