#4 tags visibility for "Shared with Watchlist" bookmarks

2 users share bookmarks with privacy set on "Shared with Watchlist".
user A see bookmarks from user B, and tags on these bookmarks (and vice-versa),
but when A is connected, B's tags are neither seen on "/populartags.php" nor "populartags.php/A" nor "populartags.php/B"