Fix value for random seed if input seed parameter

[pragmaticTNT]

Many modules have a private _seed parameter. Currently, when initializing with a seed parameter, _seed is set to the logical or of this value and a pseudorandom string. Instead, I believe that the intended behaviour is to set _seed to seed and only generate the pseudorandom string if seed is null.

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[vezhnick]

This fixes the case when seed=0, which would have made self._seed = seed or random.getrandbits(63) assign random sample to the seed