fromutc: dt.tzinfo is not self: pytz.timezone('UTC').fromutc(datetime.utcnow())

[aspineux]

hi

>>> import pytz
>>> from datetime import datetime
>>> pytz.timezone('GMT0').fromutc(datetime.utcnow())
datetime.datetime(2011, 10, 19, 7, 54, 45, 579125,
tzinfo=<StaticTzInfo 'GMT0'>)
>>>  pytz.timezone('UTC').fromutc(datetime.utcnow())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: fromutc: dt.tzinfo is not self
>>> pytz.timezone('Europe/Brussels').fromutc(datetime.utcnow())
datetime.datetime(2011, 10, 19, 9, 55, 47, 787937, tzinfo=<DstTzInfo
'Europe/Brussels' CEST+2:00:00 DST>)

Why does UTC fail ?
Bug or feature ?