I have included code from others trusting that it would work, and that they would fix reported problems. And often that is true, there are quite a few faithful contributors. But sometimes someone just wants to get his feature in, and as soon as the things he uses are working, he disappears. And then I end up having to fix problems. These days I’m a lot more careful about including new features. Especially when it’s complex and interferes with several existing parts of the code. I’m insisting more often on writing tests and documentation before including anything.