This code allows you to persist a database between test runs. It is really useful for running the same tests again and again, without incurring the cost of having to re-create the database each time.
To call this function, simply use the quicktest management command, instead of the test command. If you need to alter the schema for your tests, simply run the normal test command, and the normal destroy/create cycle will take place.
The functionality is actually implemented in a Test Runner located at test_utils.test_runners.keep_database. If you want to use this as your default test runner, you can set the TEST_RUNNER setting to that value. This is basically all that the management command does, but in a temporary way.