Iron golems spawning in slabs

Whnere i have built my iron golem farm i have a sugar cane farm 7 blocks away and often the Iron Golems are Spawning inside slabs where they should'nt be able to as seen by the picture. This was prev marked as fixed in MC-3927 but thought a new report would be required.

https://puu.sh/FDYpx/d815dc972f.jpg