Small performance tweak - avoid loading django.core.management in DB backend code

import time

from django.conf import settings

from django.core.management import call_command

# The prefix to put on the default database name when creating

# the test database.

        Creates a test database, prompting the user for confirmation if the

        database already exists. Returns the name of the test database created.

        """

        # Don't import django.core.management if it isn't needed.

        from django.core.management import call_command

        test_database_name = self._get_test_db_name()

        if verbosity >= 1: