Rob Moore

Ah, it was a duplicate after all; my bad, I searched specifically for villagers and kelp so I didn't find MC-136318.

I've made this a bit more general as I've just tried it in creative and found that pigs behave the same way, so it's probably all mobs.

Set up was a 4 x 5 tank containing water 4 blocks deep and with kelp filling every water block, with two narrow platforms on either side of the tank and walls around it to keep the mobs in. I watched a villager enter the tank, cross a couple of the kelp blocks, but then get stuck on one and exhibit the spinning behaviour I described. I then lured a pig in with wheat and it did the same thing; neither mob were constantly spinning, sometimes they stopped and looked at me, but they never budged off of the block they got stuck on at all, and even trying to lure the pig off of it with wheat had no effect.

EDIT: Of course, since pigs haven't been lured by wheat for about 4-5 years, that could have something to do with it :facepalm:

I have uploaded the screenshot birch-replaces-wall.png to demonstrate that birch leaves still replace mossy cobblestone wall as of 1.4.4. The red dots point out the only 3 wall blocks remaining of what was previously a complete square.

This also happens with jungle trees.

I just tried again and I can confirm that the bug still exists for both jungle trees and birch trees. I also tried oak and pine trees, but neither appeared able to replace mossy cobblestone wall during my attempts. Richard Cox seems to be correct, this only happens for Birch and Jungle trees.

Re Richard Cox: I am unable to recreate the problem in 1.4.4; when using bonemeal to grow an oak tree, the leaves no longer replace blocks: I have tried this with fence, nether brick fence, mossy cobblestone wall, and glass blocks. Leaves are missing where these blocks obstruct them, or the tree is entirely unable to grow. This is shown in the attached screenshot (tree-obstructed.jpg). The bug appears to have been resolved.