0 and None are being shown as an empty string in fields

When trying to use a HiddenField for an id I noticed that its treating 0 as "" as well as doing the same for None. This shows up in atleast IntegerField as well. Included below is a unit test showing the problem.

{{{
#!python

import unittest
from wtforms import Form, HiddenField

class Foo(Form):
id = HiddenField()

class TestHiddenField(unittest.TestCase):
def setUp(self):
self.f = Foo()

suite = unittest.TestLoader().loadTestsFromTestCase(TestHiddenField)
unittest.TextTestRunner(verbosity=2).run(suite)

}}}

this gives me

{{

{ test_0_data_is_0 (*main*.TestHiddenField) ... FAIL\\ test_none_data_is_blank (*main*.TestHiddenField) ... ok h2. ======================================================================\\ FAIL: test_0_data_is_0 (*main*.TestHiddenField) Traceback (most recent call last):\\ File "C:\eclipse\workspace\renderranch\test.py", line 17, in test_0_data_is_0\\ self.assertEqual(str(self.id),'<input id="id" name="id" type="hidden" value="0" />')\\ AssertionError: '<bound method TestHiddenField.id of <*main*.TestHiddenField testMethod=test_0_data_is_0>>' != '<input id="id" name="id" type="hidden" value="0" />' ---- Ran 2 tests in 0.000s FAILED (failures=1) }

}}