Historical Rules · 10 August 2018
Rule 701.19b
Official source text from the 10 August 2018 Rules release
Some effects cause a player to search a library for a card or cards, shuffle that library, then put the found card or cards in a certain position in that library. Even though the found card or cards never leave that library, they aren’t included in the shuffle. Rather, all the cards in that library except those are shuffled. Abilities that trigger when a library is shuffled will still trigger. See also rule 401, “Library.”