The Bug
Iron golems have no leg animation. They also don't wave their bodies when they walk
Edit 1.9.0.2:
Iron golems got their leg animation back but their bodies are still stiff when they walk. Also their arms are tilted slightly backwards
How to reproduce
Summon an iron golem
Have it walk around
Closing ticket. Please refer to MCPE-39548 for the related issue with Iron Golem model animation.