Fixed #15582 -- Documented how TransactionTestCase.multi_db affects fixtures.

can be certain that the outcome of a test will not be affected by another test,

or by the order of test execution.

By default, fixtures are only loaded into the ``default`` database. If you are

using multiple databases and set :attr:`multi_db=True

<TransactionTestCase.multi_db>`, fixtures will be loaded into all databases.

URLconf configuration

~~~~~~~~~~~~~~~~~~~~~

This test case will flush *all* the test databases before running

``testIndexPageView``.

The ``multi_db`` flag also affects into which databases the

attr:`TransactionTestCase.fixtures` are loaded. By default (when

``multi_db=False``), fixtures are only loaded into the ``default`` database.

If ``multi_db=True``, fixtures are loaded into all databases.

.. _overriding-settings:

Overriding settings