Fixed #9411 -- Changed the test from r9081 to be more robust across different database backends.

>>> expected == result

True

Make sure bump_prefix() (an internal Query method) doesn't (re-)break.

>>> query = Tag.objects.values_list('id').order_by().query

>>> query.bump_prefix()

>>> print query.as_sql()[0]

SELECT U0."id" FROM "queries_tag" U0

Make sure bump_prefix() (an internal Query method) doesn't (re-)break. It's

sufficient that this query runs without error.

>>> qs = Tag.objects.values_list('id', flat=True).order_by('id')

>>> qs.query.bump_prefix()

>>> list(qs)

[1, 2, 3, 4, 5]

Calling order_by() with no parameters removes any existing ordering on the

model. But it should still be possible to add new ordering after that.