What about using a combination of revision control and unit-tests? A given unit test serves as the annotation for a static piece of functionality. The evolutio

What about using a combination of revision control and unit-tests? A given unit test serves as the annotation for a static piece of functionality. The evolution of the code behind the unit-test shows the pre-bug (French) and post-bug (English) states. A little harebrained perhaps, but there are a lot of open source projects with a long history behind them; maybe there are a few viable candidates to test this on.