Wrong documentation for changing Model formsets queryset

[Claude Paroz]

In the documentation, we can read that a Model Formset queryset can be changed with the following code:

class BaseAuthorFormSet(BaseModelFormSet):
    def __init__(self, *args, **kwargs):
        self.queryset = Author.objects.filter(name__startswith='O')
        super(BaseAuthorFormSet, self).__init__(*args, **kwargs)

See ​http://docs.djangoproject.com/en/dev/topics/forms/modelforms/#changing-the-queryset

This doesn't work. The problem is that in the __init__ function of BaseModelFormSet, the queryset is redefined from the queryset parameter which default to None.
See ​http://code.djangoproject.com/browser/django/trunk/django/forms/models.py#L448

To make it work, the queryset should be added to the __init__ call as a keyword parameter. Or it might also be a bug in the __init__ function where it should test if self.queryset is not None before assigning to it. Either in docs, either in code, I think there is something to solve.

[Tim Graham]

switch the order of super/self.queryset lines

[Russell Keith-Magee]

(In [13553]) Fixed #11735 -- Corrected an example of FormSet subclassing. Thanks to claudep for the report.

[Russell Keith-Magee]

(In [13560]) [1.2.X] Fixed #11735 -- Corrected an example of FormSet subclassing. Thanks to claudep for the report.

Backport of r13553 from trunk.