SetValues incorrectly sets timestamp values

This line seems to be overwriting all timestamp values with the current time:

Line 44 in c2a1568

    
           values = {key: (val.utcnow().isoformat() if isinstance(val, datetime) else val) for (key, val) in self.values.items() }

Specifically at this part: val.utcnow().isoformat() if isinstance(val, datetime)

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