What was the issue that was evidently so contentious that it made him wish to step down?
replies(5):
Naturally people went to the barricades for it, in a classic example of bikeshedding and Wadler's Law (programmers will fight to the death over trivial syntax disagreements and just shrug at profound changes to semantics and architecture)
That's not it at all. The PEP even acknowledges that while `(a := b)` would be valid, it would not be recommended.