Axolotls play dead even when they take damage without being attacked by an entity

The Bug

Axolotls turn into the fatal death position (when they pretends to be dead and gaining regeneration effect) even when they are damaged by block (for exaple cacti or campfire), wich is very weird.

 

How to Reproduce

1. Get axolotl spawn egg and something which is not entity and gives damage
2. Put axolotl on that