fix r9713 for #36565

Authorised by: AcydBurn

git-svn-id: file:///svn/phpbb/branches/phpBB-3_0_0@9931 89ea8834-ac86-4346-8a33-228a782c2dd0

phpBB/install/database_update.php

@@ -721,6 +721,9 @@ function database_update_info()
 					'post_id'		=> array('post_id'),
 					'pm_id'			=> array('pm_id'),
 				),
+				POSTS_TABLE			=> array(
+					'post_username'		=> array('post_username'),
+				),
 			),
 		),
 	);