def initial_form_count(self):
        if self.is_bound:
            return 0
        return super(BaseStepFormSet, self).initial_form_count()
Consider all forms 'extra' when bound so ModelFormSet won't look up PK.
dataset/ETHPy150Open mozilla/moztrap/moztrap/view/manage/cases/forms.py/BaseStepFormSet.initial_form_count