Avoided modifying current environment in admin_scripts tests

        django_dir = os.path.dirname(tests_dir)

        ext_backend_base_dirs = self._ext_backend_paths()

        # Remember the old environment

        old_django_settings_module = os.environ.get('DJANGO_SETTINGS_MODULE', None)

        # Define a temporary environment for the subprocess

        test_environ = os.environ.copy()

        if sys.platform.startswith('java'):

            python_path_var_name = 'JYTHONPATH'

        else:

            python_path_var_name = 'PYTHONPATH'

        old_python_path = os.environ.get(python_path_var_name, None)

        old_cwd = os.getcwd()

        # Set the test environment

        if settings_file:

            os.environ['DJANGO_SETTINGS_MODULE'] = settings_file

        elif 'DJANGO_SETTINGS_MODULE' in os.environ:

            del os.environ['DJANGO_SETTINGS_MODULE']

            test_environ['DJANGO_SETTINGS_MODULE'] = settings_file

        elif 'DJANGO_SETTINGS_MODULE' in test_environ:

            del test_environ['DJANGO_SETTINGS_MODULE']

        python_path = [base_dir, django_dir, tests_dir]

        python_path.extend(ext_backend_base_dirs)

        os.environ[python_path_var_name] = os.pathsep.join(python_path)

        test_environ[python_path_var_name] = os.pathsep.join(python_path)

        # Move to the test directory and run

        os.chdir(test_dir)

        out, err = subprocess.Popen([sys.executable, script] + args,

                stdout=subprocess.PIPE, stderr=subprocess.PIPE,

                universal_newlines=True).communicate()

        # Restore the old environment

        if old_django_settings_module:

            os.environ['DJANGO_SETTINGS_MODULE'] = old_django_settings_module

        if old_python_path:

            os.environ[python_path_var_name] = old_python_path

                env=test_environ, universal_newlines=True).communicate()

        # Move back to the old working directory

        os.chdir(old_cwd)