pytz recommends normalize() method instead of astimezone() here:

  >>> tzlocal.get_localzone().normalize(pytz_time - timedelta(seconds=1))
  datetime.datetime(2015, 10, 25, 2, 59, 59, tzinfo=<DstTzInfo 'Europe/Paris' CEST+2:00:00 DST>)

The result is the same in this case.

It is a _fact_. It is how python behaves now on my platform.