Yes, I'm more disappointed that this wasn't picked up by an automated test suite than the fact that it might take a few days to patch.
Surely someone, somewhere is at least creating daily snapshots of the code and putting it through fuzzers and stress-tests and simulated disk-full situations? If not, why not? This is filesystem code we're talking about, not the backend of some casual game.
There was a .ksh in the commit specifically to test this feature, but it looks a bit spartan for what could be a huge data loss bug (as practically any filesystem bug is).