Weird timezone issue with pytz

Time zones and offsets change over the years. The default zone name and offset delivered when pytz creates a timezone object are the earliest ones available for that zone, and sometimes they can seem kind of strange. When you use localize to attach the zone to a date, the proper zone name and offset are substituted. Simply using the datetime constructor to attach the zone to the date doesn't allow it to adjust properly.

While I'm sure historic changes in timezones are a factor, passing pytz timezone object to the DateTime constructor results in odd behavior even for timezones that have experienced no changes since their inception.

import datetime
import pytz 

dt = datetime.datetime(2020, 7, 15, 0, 0, tzinfo= pytz.timezone('US/Eastern'))

produces

2020-07-15 00:00:00-04:56

Creating the datetime object then localizing it produced expected results

import datetime
import pytz 

dt = datetime.datetime(2020, 7, 15, 0, 0)
dt_local = timezone('US/Eastern').localize(dt)

produces

2020-07-15 00:00:00-04:00