Order of files and directories given to phpbb_test_case_helpers->remove_files() matters.

PHP Warning:  rmdir(phpBB/ext/./foo): Directory not empty in /var/www/projects/phpbb3/tests/test_framework/phpbb_test_case_helpers.php on line 269

PHP Stack trace:

PHP   1. {main}() /usr/bin/phpunit:0

PHP   2. PHPUnit_TextUI_Command::main() /usr/bin/phpunit:46

PHP   3. PHPUnit_TextUI_Command->run() /usr/share/php/PHPUnit/TextUI/Command.php:129

PHP   4. PHPUnit_TextUI_TestRunner->doRun() /usr/share/php/PHPUnit/TextUI/Command.php:176

PHP   5. PHPUnit_Framework_TestSuite->run() /var/www/projects/phpbb3/phpBB/vendor/phpunit/phpunit/PHPUnit/TextUI/TestRunner.php:349

PHP   6. PHPUnit_Framework_TestSuite->run() /var/www/projects/phpbb3/phpBB/vendor/phpunit/phpunit/PHPUnit/Framework/TestSuite.php:705

PHP   7. call_user_func() /var/www/projects/phpbb3/phpBB/vendor/phpunit/phpunit/PHPUnit/Framework/TestSuite.php:756

PHP   8. phpbb_functional_extension_acp_test::tearDownAfterClass() /var/www/projects/phpbb3/phpBB/vendor/phpunit/phpunit/PHPUnit/Framework/TestSuite.php:756

PHP   9. phpbb_test_case_helpers->restore_original_ext_dir() /var/www/projects/phpbb3/tests/functional/extension_acp_test.php:33

PHP  10. phpbb_test_case_helpers->remove_files() /var/www/projects/phpbb3/tests/test_framework/phpbb_test_case_helpers.php:64

PHP  11. rmdir() /var/www/projects/phpbb3/tests/test_framework/phpbb_test_case_helpers.php:269