Change in datetime type casting

From the docs:
>>> dt = datetime.datetime.now()
>>> dt
datetime.datetime(2010, 2, 8, 1, 40, 27, 425337)

>>> cur.mogrify("SELECT %s, %s, %s;", (dt, dt.date(), dt.time()))
"SELECT '2010-02-08T01:40:27.425337', '2010-02-08', '01:40:27.425337';"

Current (2.4.3) behavior:
dt
Out[28]: datetime.datetime(2012, 6, 27, 16, 11, 33, 125585)

cur1.mogrify("SELECT %s, %s, %s;", (dt, dt.date(), dt.time()))
Out[30]: "SELECT '2012-06-27T16:11:33.125585'::timestamp,
'2012-06-27'::date, '16:11:33.125585'::time;"

Note the addition of the casts. This is causing problems when using the
hstore adapter as hstore expects a plain string. Is there a way to get
around this?

--
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com