I am surprised I have not seen anyone mention this yet but a simple regression with line coverage enabled would have caught this. Is it not common in the software community (I do mainly Hardware) to run regularly with line coverage? This seems like a basic problem with process in my opinion.

My experience says it's uncommon. Microsoft seems pretty good about it, and has good tools available, though it might vary a lot from team to team. Smaller companies? I've at times been revered as a testing deity when showing someone code coverage results. Other companies know what the word "coverage" means, but seldom know about or utilize the tools available. They just know they probably ought to do it, which is a step ahead, I guess.

Where I'm currently at, my manager wanted code coverage but needed someone to do it. Since I'm just that guy, I setup the infrastructure for iOS. Android, you're such a pain in the ass to setup for (rooted device, or the dog-slow emulator, and it still doesn't give me results) I'm surprised anyone does code coverage for Android. I can't remember the name of the python tool, but holy smokes it's slick and painless.

So tooling quality varies, which might have a lot to do with the lack of coverage testing. I long for the days of the coverage tool Tim Paterson wrote (yeah, that Tim Paterson). No profiling, it would inject the coverage DLL at runtime. Then, as you used the program, it would log coverage on the fly. So program running on one monitor, coverage log on the other, and start clicking. Can't remember the name of it (it's no longer sold by Paterson Technologies), but damn it was slick.