I actually found an OS bug in AIX on my first real I-designed-this code project. Worse, the bug was discovered only when the code went into production - it beha

I actually found an OS bug in AIX on my first real I-designed-this code project. Worse, the bug was discovered only when the code went into production - it behaved differently on the test servers than on the production servers! The bug caused mmap() system calls to randomly overwrite certain pages in memory with NULLs. Yeah, that was fun. And it was caused by the order in which patches had been applied, which was why it behaved differently in production than in dev/test. If some second year programmer told me that nonsense, I'd make them go back and either find their bug, or write a test program that exercised the bug in isolation (which was what I did).