Added changes missing from previous commit.

When a :class:`~django.db.models.BooleanField` doesn't have an explicit

:attr:`~django.db.models.Field.default`, the implicit default value is

``None``. In previous version of Django, it was ``False``, but that didn't

represent accurantely the lack of a value.

represent accurately the lack of a value.

Code that relies on the default value being ``False`` may raise an exception

when saving new model instances to the database, because ``None`` isn't an

acceptable value for a :class:`~django.db.models.BooleanField`. You should

either specify ``default=False`` explicitly on the field definition, or ensure

the field is set to ``True`` or ``False`` before saving the object.

either specify ``default=False`` in the field definition, or ensure the field

is set to ``True`` or ``False`` before saving the object.

Translations and comments in templates

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~