In my 1.7.9 world I built a massive gold farm using Nether portal whose floor was removed. I plan to update my save soon so I’m testing if everything works fine in a copy of the world. While doing so, I discovered that Zombie Pigmen didn’t spawn anymore on this farm. This happens from snapshot 19w12b onwards.

After researching the latest version, I noticed that the algorithm that looks for a floor to spawn the Zombie Pigmen (at NetherPortalBlock.randomTick) keeps iterating only while it finds NetherPortalBlock instead of non-solid blocks as it used to be. Reverting this change does not damage nor benefit the standard game, given that usually there are no portals without floor, but it saves these extremely uncommon farms. I spent hundreds of hours building the farm, I beg you to change this back.