form instance is incorrectly propagated to other forms

[marcinn]

if instance is None a previous kwargs dictionary is used in next iteration.
Affected code (forms.CompositeForm.__init__):

        for form in self.form_list:
            if self.get_form_instance(form):
                kwargs.update({"instance": self.get_form_instance(form)})
            self._form_instances[form] = form(data, files, *args, **kwargs)

a possible fix:

        for form in self.form_list:
            kwargs = initkwargs.copy()
            if self.get_form_instance(form):
                kwargs.update({"instance": self.get_form_instance(form)})
            self._form_instances[form] = form(data, files, *args, **kwargs)

[t0ster]

Can you provide sample code of how to reproduce bug.

Thanks!

[marcinn]

Some like this:

class MyForm(CompositeForm):
  form_list = UserModelForm, ModelForm1, ModelForm2

def object_create(request):
  form = MyForm(data=request.POST, instances=[request.user, None, None])

in first iteration you have an User instance that is reused for ModelForm1 and ModelForm2

[t0ster]

Thanks!