Form subclass trying to override parent form field

[nwp]

If a form subclass tries to override a parent form's field definition, the definition is overridden but the field is repeated.

class FormA(forms.Form):
    somefield = forms.AnyField(anyargs)

class FormB(FormA):
    somefield = forms.OtherField(otherargs)

FormB ends up with *two* somefields, both forms.Otherfield. This seems to me to be a bug in DeclarativeFieldsMetaclass's __new__ method - I think it should do some checking for duplicates round about as it adds fields to base_fields.

This is svn r6471.

[Matt McClanahan]

Fixed in [6668].