Fixed #10181 -- Handle an EmptyResultSet exception case properly in nested querysets.

        if hasattr(obj, "process"):

            try:

                obj, params = obj.process(lookup_type, value)

            except EmptyShortCircuit:

            except (EmptyShortCircuit, EmptyResultSet):

                # There are situations where we want to short-circuit any

                # comparisons and make sure that nothing is returned. One

                # example is when checking for a NULL pk value, or the

[<Annotation: a1>]

Nested queries should not evaluate the inner query as part of constructing the

SQL. This test verifies this: if the inner query is evaluated, the outer "in"

lookup will raise an EmptyResultSet exception (as the inner query returns

nothing).

>>> print Annotation.objects.filter(notes__in=Note.objects.filter(note="xyzzy")).query

SELECT ...

SQL (so we should see a nested query here, indicated by two "SELECT" calls).

>>> Annotation.objects.filter(notes__in=Note.objects.filter(note="xyzzy")).query.as_sql()[0].count('SELECT')

2

Bug #10181 -- Avoid raising an EmptyResultSet if an inner query is provably

empty (and hence, not executed).

>>> Tag.objects.filter(id__in=Tag.objects.filter(id__in=[]))

[]

Bug #9997 -- If a ValuesList or Values queryset is passed as an inner query, we

make sure it's only requesting a single value and use that as the thing to