ValueError exception when asking for authored_datetime #741

> from git import Repo
> repo = Repo('rails')
> commit = repo.commit('4cf94979c9f4d6683c9338d694d5eb3106a4e734')
> commit.authored_datetime
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/dspadini/Documents/pydriller/.venv/lib/python3.6/site-packages/git/objects/commit.py", line 151, in authored_datetime
    return from_timestamp(self.authored_date, self.author_tz_offset)
  File "/Users/dspadini/Documents/pydriller/.venv/lib/python3.6/site-packages/git/objects/util.py", line 124, in from_timestamp
    > local_dt = utc_dt.astimezone(tzoffset(tz_offset))
ValueError: offset must be a timedelta strictly between -timedelta(hours=24) and timedelta(hours=24).

local_dt = utc_dt.astimezone(tzoffset(tz_offset))

class tzoffset(tzinfo):
    def __init__(self, secs_west_of_utc, name=None):
        self._offset = timedelta(seconds=-secs_west_of_utc)
        print('Timedelta is {}'.format(timedelta(seconds=-secs_west_of_utc)))