Inconsistent relativedelta args checking

current relativedelta.__init__() method performs type checking mixing isinstance() and type() == type() checks leading to inconsistent results. I've been bitten by a bug when comparing a datetime.date with a FakeDatetime from python-freezegun:

File "/usr/local/lib/python2.7/dist-packages/dateutil/relativedelta.py", line 146, in __init__
    if dt1 < dt2:
TypeError: can't compare FakeDatetime to datetime.date

current checking is

if (not isinstance(dt1, datetime.date)) or (not isinstance(dt2, datetime.date)):
    raise TypeError("relativedelta only diffs datetime/date")
if not type(dt1) == type(dt2) # isinstance(dt2, type(dt1)):
    if not isinstance(dt1, datetime.datetime):
        dt1 = datetime.datetime.fromordinal(dt1.toordinal())
    if not isinstance(dt2, datetime.datetime):
        dt2 = datetime.datetime.fromordinal(dt2.toordinal())

I think a more consistent one, using always isinstance(), could be:

if (not isinstance(dt1, datetime.date)) or (not isinstance(dt2, datetime.date)):
    raise TypeError("relativedelta only diffs datetime/date")
if not isinstance(dt1, type(dt2)):
    if not isinstance(dt1, datetime.datetime):
        dt1 = datetime.datetime.fromordinal(dt1.toordinal())
    else:
        dt2 = datetime.datetime.fromordinal(dt2.toordinal())