Druid in a tiny space revert to normal form

@zolt4rWhat happen if a Druid shaped in fish or bird will take more hp damage than is form can have in a tiny space?
We’ll have to cover that in the rules, but I’d push the druid to nearest large space, druid takes damage equal to distance in feet.

— Mike Mearls (@mikemearls) October 21, 2013

This advice was made during playtest but could be useful for Wild shape and Polymorph spell.