"The second 'bug' is even stranger. A heuristic arose which (as part of a daring but ill-advised experiment EURISKO was conducting) said that all machine-synthesized heuristics were terrible and should be eliminated. Luckily, EURISKO chose this very heuristic as one of the first to eliminate, and the problem solved itself."

I know it's not strictly comparable, but reading a couple of comments brought this to mind.