[ticket/14008] Do not add a user_id value to quotes from guests

PHPBB3-14008

tests/text_formatter/s9e/utils_test.php

@@ -175,6 +175,15 @@ class phpbb_textformatter_s9e_utils_test extends phpbb_test_case
 				),
 				'[quote=user post_id=123 url=http://example.org]...[/quote]',
 			),
+			array(
+				'...',
+				array(
+					'author'  => 'user',
+					'post_id' => 123,
+					'user_id' => ANONYMOUS
+				),
+				'[quote=user post_id=123]...[/quote]',
+			),
 			array(
 				'...',
 				array('author'  => ' '),