Fix incorrect seed initialization when args.seed is 0

[azolotenkov]

What does this PR do?

When args.seed is set to 0, the condition if args.seed else None evaluates to None because 0 is considered a falsy value in Python. This results in None being assigned instead of 0, which can cause unintended behavior when initializing the random generator.

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Who can review?

@sayakpaul

[sayakpaul]

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