[vacri]

The first rule is that you don't break userspace, not that you don't make mistakes. Commits go through a process before being put into the kernel, and if yours is going to break userspace, it won't get in, so don't expect it to. You can make mistakes, but if they're found, you're expected not to say "well, commit it anyway". It's not the mistake that the violation of the rule, but the cavalier attitude.