Kent wanted to merge new features after the merge window had been closed (bundled with a bug fix) and Linus said no and since this was not the first time Kent tried to do something like that people got angry at him. And since Kent refused to apologize for repeatedly breaking the rules things got heated.
In Kent's opinion the features were important to maintaining greater data integrity and recovering from various problems. Nobody else agreed and Kent wasn't taking no for an answer even from Linus.
