Stackdistiller converts all times to utc.

        We store timestamps as utc datetime. However, the explicit
        UTC timezone on incoming datetimes causes comparison issues
        deep in sqlalchemy. We fix this by converting all datetimes
        to naive utc timestamps

def _fix_time(self, dt):
        """Stackdistiller converts all times to utc.

        We store timestamps as utc datetime. However, the explicit
        UTC timezone on incoming datetimes causes comparison issues
        deep in sqlalchemy. We fix this by converting all datetimes
        to naive utc timestamps
        """
        if dt.tzinfo is not None:
            dt = dt.replace(tzinfo=None)
        return dt