Some entities are not regarded as obstructions by mob pathfinding

Some extra info: In theory this applys to all mobs in that they can hinder other mobs in going to where they want if the first mob is blocking their path. But since mobs usually moves around, this problem fixes itself. But for the Shulkre Mob which remains stationary unless it is provoked to teleport away (if at all possible for it) and the boat which also stays stationary, this poses a problem when a mob is fixed on pathing through it but unable to do so. Also the fact that a mob is unable to push a shulker or a boat.
Perhaps mobs Pathfinding AI should consider the hitbox of other entities as actually blocking a path in the same way as they see blocks.

@pelle Entities pathfind through boats and minecarts they just get trapped inside of them which is a good thing. It makes it less difficult to catch them for transport. Methinks i see what you mean with the shulkers though. For instance, the cows i have, will cluster in a corner and continue to try to get through. 

Merged into MC-94831