- _new_publishable = models.NullBooleanField(editable=False)
- _published = models.NullBooleanField(editable=False)
- _changed = models.NullBooleanField(editable=False)
+ _new_publishable = models.BooleanField(editable=False, null=True)
+ _published = models.BooleanField(editable=False, null=True)
+ _changed = models.BooleanField(editable=False, null=True)