not only does every test have to pass, but that the commit can't delete any code from a test.

Good idea, but this is easily gamed by e.g. adding a test that starts failing on a certain date. I've thought about this before, and it's really hard to come up with mechanisms for a system to incorporate untrusted modifications without totally collapsing.

It would be hilarious to design a program that accepts Bitcoin payments, and automatically accepts merge requests from the highest bidder.