Per report on mw:Parsoid/Feedback, [[://Hus]] is supposed to link to https://en.wikipedia.org/wiki///Hus, but Parsoid links it to a subpage //Hus of the page in which the wikitext is found.
See https://en.wikipedia.org/wiki/Help:Colon_trick?useparsoid=1#Examples vs https://en.wikipedia.org/wiki/Help:Colon_trick?useparsoid=0#Examples
Colon followed by a single slash also fails in Parsoid. [[:/Film]] is supposed to link the mainspace page "/Film" but outside mainspace it links a /Film subpage like if there was no colon. Compare the [[:/Film]] link without Parsoid and with Parsoid. It only fails with Parsoid.
Ive been here 20 years and today i learned about the “colon trick” escaping titles starting with /…. God i hate wikicode sometimes ;)