Rows.as_json failing with default JSON about pydal HOT 9 CLOSED

>>> from pydal import DAL, Field
>>> from datetime import datetime
>>> db.define_table('test', Field('a'), Field('date', 'datetime'))
<Table test (id,a,date)>
>>> from datetime import datetime
>>> db.test.insert(a='asd', date=datetime.utcnow())
2L
>>> rows = db(db.test.id > 0).select()
>>> rows.as_json()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/dominic/work/web2py/gluon/packages/dal/pydal/objects.py", line 2717, in as_json
    return json.dumps(items)
  File "/usr/lib64/python2.7/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib64/python2.7/json/encoder.py", line 201, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib64/python2.7/json/encoder.py", line 264, in iterencode
    return _iterencode(o, 0)
  File "/usr/lib64/python2.7/json/encoder.py", line 178, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: datetime.datetime(2015, 4, 20, 15, 2, 39) is not JSON serializable
>>> rows[0].as_json()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/dominic/work/web2py/gluon/packages/dal/pydal/objects.py", line 213, in as_json
    return json.dumps(item)
  File "/usr/lib64/python2.7/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib64/python2.7/json/encoder.py", line 201, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib64/python2.7/json/encoder.py", line 264, in iterencode
    return _iterencode(o, 0)
  File "/usr/lib64/python2.7/json/encoder.py", line 178, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: datetime.datetime(2015, 4, 20, 15, 2, 39) is not JSON serializable
>>>