UTC offsets seem to be wrong

[Ngg971]

Hi,

I am using your library extensively and love it. However recently I noticed what I believe is a bug in the UTC offsets for various timezones. It seems related to a 'premptive' switch back from daylight savings.

For example, here I create a naive datetime (2018-02-01 6:00:00) and localize it to the London timezone. However when I print the tz-aware datetime object, it shows GMT0:00:00 and when I print the utcoffset() it also shows a difference of 0:00:00.

>>> local_date
datetime.datetime(2015, 2, 1, 6, 0)
>>> res_timezone_one
<DstTzInfo 'Europe/London' LMT-1 day, 23:59:00 STD>
>>> aware_datetime = res_timezone_one.localize(local_date)
>>> aware_datetime
datetime.datetime(2015, 2, 1, 6, 0, tzinfo=<DstTzInfo 'Europe/London' GMT0:00:00 STD>)
>>> aware_datetime.utcoffset()
datetime.timedelta(0)

This is wrong, as London is one hour ahead of GMT at the moment (until October 28th). I am also getting a similar problem with America/Denver.

Thanks,
Nathanael