Have you ever had a software problem that disappeared even when you did nothing to correct it? Or have you ever fixed a bug by doing something that seems as if it shouldn’t have fixed anything?
Whenever that happens to me, I A) remain wary, and B) remove the fix so that by seeing the problem again I have additional evidence that the “fix” was truly the fix. I call this is the dead bee heuristic, because if there’s a bee in my living room, I don’t want it to mysteriously disappear, I want to see it fly out my window or be dead on my floor.
This applies to testing situations, too. If I change a data file and see that it no longer crashes the application I’m testing, the next thing I do is change it back again so I can see the crash one more time.
“Say, was you ever bit by a dead bee?…You know, you got to be careful of dead bees if you’re goin’ around barefooted, ’cause if you step on them they can sting you just as bad as if they was alive, especially if they was kind of mad when they got killed. I bet I been bit a hundred times that way.” — Walter Brennan as “Eddie” in To Have and Have Not
And always bear in mind that killing the “bee” may not have solved the real problem, or may have created new problems.