Datetime, pytz and strange offset

[David Pratt]

Hi. I am creating a couple of small methods to help me manage time from 
UTC as standard but I am getting strange results.

If I start with a datetime of 2005-12-12 14:30:00 in timezone 
'America/Halifax'
and I want to turn this into a UTC representation.

from datetime import datetime
from pytz.reference import UTC
import pytz

fmt = '%Y-%m-%d %H:%M:%S %Z%z'
tz = pytz.timezone('America/Halifax')
dt = datetime(year=2005, month=12, day=11, hour=14, minute=30, second=0, 
microsecond=0, tzinfo=tz)
print dt.strftime(fmt)

This is giving me a strange offset of -0414 and LMT timezone.
ie. 2005-12-12 14:30:00 LMT-0414
I am not sure where this is coming from

To get the utc equivalent using dt = dt.astimezone(UTC) I get this 
strange result which is obviously also not correct:
# '2005-12-12 18:44:00 UTC+0000'

If I do datetime.now instead with the same timezone I get the correct 
timezone and correct offset.

ie.
dt = datetime.now(tz=tz)
# '2005-12-12 21:37:17 AST-0400'

If I get now time from this as utc it is correct
dt = dt.astimezone(UTC)
# '2005-12-12 01:37:17 UTC+0000'

If I do a different timezone of 'America/Vancouver'
I get something appropriate for the 2:30 case

tz = pytz.timezone('America/Vancouver')
dt = datetime(year=2005, month=12, day=12, hour=14, minute=30, second=0, 
microsecond=0, tzinfo=tz)
print dt.strftime(fmt)
# 2005-12-12 20:30:00 PST-0800

I am not sure why I am getting  -0414 and LMT for 'America/Halifax' 
timezone? Is this a bug in the pytz package? Many thanks.

Regards,
David