Gelbooru only allows to retrieve the latest 20k posts for a tag search.
Add 'id:<N' to the search tags to work around that limitation, where N
is the ID of the last retrieved post.
http://gelbooru.me/index.php?page=forum&s=view&id=1467
* [booru] add an option to extract notes (currently implemented only for gelbooru)
* appease linter
* [gelbooru] rename "text" to "body" in note extraction
* add a code comment about reusing return value of _extended_tags