Not just humility: the author goes on to explain all his practices to defend himself from himself. These attracted my attention, for no programmer I know enjoys them:

3) Be a testing masochist, i.e., I ruthlessly try to break my own code.

4) Have other programmers inspect my code.

The author goes on to explain how he approached fixing a broken program: to stop catching errors and letting it crash. Which meant getting stack traces and fixing them on the spot. Combined with his aggressive use of assertions, no wonder he fixed it.