Hmm. Unfortunately then it seems that either way, some people will be upset, but now I don't know which way it was originally meant to be! But I can say with certainty that golems don't spawn in slabs as of 18w30b (I tested this using one of those spawn pads i mentioned), so MC-3927 should be marked as resolved now. Anyway, I believe that it would have been better to keep golem spawning the way it was in 1.12, when they could spawn in slabs, so that existing farms can continue to work in 1.13 as they have been in previous versions.
Hmm. Unfortunately then it seems that either way, some people will be upset, but now I don't know which way it was originally meant to be! But I can say with certainty that golems don't spawn in slabs as of 18w30b (I tested this using one of those spawn pads i mentioned), so MC-3927 should be marked as resolved now.
Anyway, I believe that it would have been better to keep golem spawning the way it was in 1.12, when they could spawn in slabs, so that existing farms can continue to work in 1.13 as they have been in previous versions.