14w20b Jumping chicken suffocates if hits head.

Just wanted someone to know, chickens have a slight glitch. I built a chicken coop for my newly hatched chickens to hide in. But I had to remove the stairs leading up in to the coop because they were somehow tripping and getting killed on the stairs. I also noticed that when jumping on to a block, if there was another block 1 space over head they would suffocate. I don't have this problem with any other animal, only chickens.