Database field user_newtalk.user_id is not the same data type as user.user_id
user_newtalk.user_id is int, while user.user_id is unsigned int
It should be the same type for consistency (and speedy join-ability)
Requested at https://www.mediawiki.org/wiki/Manual_talk:User_newtalk_table#user_newtalk.user_id