Fixed #26324 -- Fixed DurationField with fractional seconds on SQLite.

            return value

        if value is None:

            return None

        return value.total_seconds() * 1000000

        # Discard any fractional microseconds due to floating point arithmetic.

        return int(round(value.total_seconds() * 1000000))

    def get_db_converters(self, connection):

        converters = []

* Made ``MultiPartParser`` ignore filenames that normalize to an empty string

  to fix crash in ``MemoryFileUploadHandler`` on specially crafted user input

  (:ticket:`26325`).

* Fixed data loss on SQLite where ``DurationField`` values with fractional

  seconds could be saved as ``None`` (:ticket:`26324`).

* Fixed a race condition in ``BaseCache.get_or_set()`` (:ticket:`26332`). It

  now returns the ``default`` value instead of ``False`` if there's an error

  when trying to add the value to the cache.

* Fixed data loss on SQLite where ``DurationField`` values with fractional

  seconds could be saved as ``None`` (:ticket:`26324`).

        loaded = NullDurationModel.objects.get()

        self.assertEqual(loaded.field, None)

    def test_fractional_seconds(self):

        value = datetime.timedelta(seconds=2.05)

        d = DurationModel.objects.create(field=value)

        d.refresh_from_db()

        self.assertEqual(d.field, value)

class TestQuerying(TestCase):