If you recommend to also look at the entire thread, I would use a link like this instead: www.elitefourum.com/t/pikachu-1st-ed-jungle-black-star-promo-was-it-intentional/26400/11 Then you can see the entire thread, but it still links to the specific post. 
But I indeed agree: great thread to read if you haven’t yet.
TL;DR: it’s likely 1st edition Ivy Pikachu promos weren’t an error, but inserted in 1st edition Jungle packs on purpose as the first English Pokémon Secret Rare card.
Greetz,
Quuador