Rat Dog

Confirming for 1.13.1:

I released this baby farmer into this pen with fully grown crops, and it immediately began farming like an adult villager. Notice how only items present in the image are the seeds and wheat from the block it just harvested, indicating it picked up the items from the other blocks it farmed. 

Note: If you follow step 3 in the original post in a valid village the babies won't farm after you kill other villagers.

I tried to reproduce this in 1.13-pre7 but couldn't. In my farm, the issue is the creepers are running, but will not run over the trapdoors. Could that be what's happening here? Hoping the trapdoor thing is fixed, because what's the point of a trapdoor you can't use as a trap. 

Attaching a screenshot of a bit of the creeper farm design I use- you can see the creepers have moved away from the cat towards the corners, but they won't go over the trapdoors. 

Tried to test on the server I use (currently on 1.13-pre6, just upgraded from 1.13-pre5), but couldn't reproduce.

Do you know what snapshot/version the horse(s) were generated/bred/egged in? I wonder if it's possible for the problem to be related to some problem in a version before 1.13-pre5, assuming the horse(s) you're having an issue with were created/generated before 1.13-pre5. (But that's just random speculation on my part..)

Still affecting 1.13-pre4 & 1.13-pre5

Confirmed 1.13-pre5 on Windows 10 operating system (if that means anything). 

I'm in survival mode in my screenshots, and I should be getting pummeled, but no shulker bullets to be found. As you can see in the first screenshot, the little poof animation happens, but no bullets produced. In the second screenshot, you can see from the subtitles that the sounds for shooting the bullets are being played normally. 

Edit: Finally had 1 bullet appear and hit me after killing ~30 shulkers by just standing directly in front of them and swording them to death with no consequences. This is a really weird bug.

Edit 2: Attempted to find conditions to reproduce that 1 shulker being able to shoot me, but have been unable to- they all just make a puff of smoke and the bullet doesn't appear.

I haven't had any turtles that don't lay eggs at all, but they take forever to do it...are you sure this isn't what is happening here? My turtles start digging up the sand, but then they stop, and do this over again multiple times over several minutes before FINALLY laying an egg. 

Just adding some details from the duplicates: 

Happens pretty much any time the player attempts to swim up from under a 1-block high space, or when swimming near a "ceiling" (any solid blocks close overhead) underwater. 

Additional info: Some have said this does not affect newly spawned villagers. This is false. When you first encounter or spawn-egg new librarian villagers in snapshot 18w22b or 18w22c, they will offer a varied assortment of book trades. HOWEVER: if you leave the area, then return to the villagers, you will find they have all become protection. This isn't even an upgrade specific issue, because it affects new worlds generated in 18w22b or 18w22c too.

Steps to reproduce:

1: Create new world in 18w22b or (18w22c) with random seed. 

2: Spawn or find librarian villagers & unlock librarian trades.

3: Place various enchanted books in a chest. 

4: Save world & close game. 

5: Reload world in snapshot selected in step 1.

6: See all villager trades and books in chest(s) are Protection I-V.

Note: The level of protection listed after the change will correspond to the level of whatever enchantment the book/villager originally had. For example, Impaling V becomes Protection V, Efficiency III will become Protection III, Mending will become Protection I. 

Affects upgrading to 18w22b from 1.12, or any of the aquatic update snapshots. This also affects upgrading to 18w22c. 

This is serious bacause it DOES affect upgrading between 1.12.2 and 18w22b- you will only see it if you load a 1.12.2 world in the snapshot, save, then reload the game in the snapshot a second time. 

Steps to reproduce:

1: Load a world in 1.12.2.

2: Place ~5 (non-Protection) enchanted books in player inventory.

3: Place ~5 (non-Protection) enchanted books in a chest.

4: Spawn or find librarian villagers & unlock librarian trades.

5: Make note of current librarian trades. 

6: Save world & close game.

7: Reload world in 18w22b.

8: See librarian trades, books in inventory and books in chest(s) have not changed. 

9: Save world & close game. 

10: Reload world again in 18w22b.

11: See books in inventory have not changed, but all villager trades and books in chest(s) are Protection I-V.

Please fix this!

It's not just existing enchanted books. It affects all librarian villager trades. They all become various levels of protection.

To reproduce:

1: Find/Breed/Spawn egg librarian villagers in 18w22a.

2: Unlock book trades for librarian villagers in 18w22a.

3: Load world in 18w22b

4: See all librarian trades have become Protection I-V.

Resolved in 18w21b. 

Here are steps to reproduce:

1. make world in snapshot 18w16c with seed -1259081801.

2. explore an area of ocean with seagrass present (this seed will spawn you on the shore directly next to the requisite ocean).

3. load the world in 18w20a, 18w20b, 18w20c, or 18w21a.

4. travel the area explored in 18w16a.

5. see seagrass in this area has been replaced with air blocks. 

6. travel further in the ocean to unexplored areas.

7. See seagrass is present and normal in newly explored areas. 

Also occuring in 18w20c, and only in old chunks (see attached screenshots of old and new chunks). I am convinced that this issue is somehow related to MC-129725, because there the lighting issue seems to occur in exactly the same way except with caves (and you know, the fact that light is going through solid blocks). I even re-did the pumpkin thing above with a weirdly-lit mineshaft and the same thing happened- although it should be noted that after the pumpkin is removed, either in the ocean or in a cave, it is still an issue because the light area stays "lit" without a light source present, only the edges smooth to blend with the dark area. 

Old chunks (Ignore air pockets, that's unrelated issue MC-129625): 

New Ocean:

Pumpkin Test in mineshaft: 

This issue affects 18w20c as well, and only in old chunks. Caves in newly generated chunks are fine. I added a spectator mode screenshot of chunks generated in 18w16a. What's really weird about this issue is that it's seemingly random. Some parts if the caves have 0 light (as they should) while with others pulling up the debug screen will show the light level as 15 sky, 0 block. If you go to one of the dark spots (0 sky, 0 block), they will light normally and update once light sources are destroyed. The light spots change with the time of day, and will always be 15 sky, 0 block, regardless of the distance from the surface. Interestingly, the light level of the light spots can be decreased slightly by placing new solid blocks overhead (the sky light level will update to between 11 & 13)- this only occurs for one layer of overhead blocks, the light level does not decrease again for subsequent layers. 

I believe this issue is also related to weird lighting on the sea floor: MC-128299. I've attached a screenshot of an unlit area of the ocean floor- as you can see, some areas appear to be lit while others do not. The "lit" areas show the sky light level to be 15, and the dark areas show the light level to be 0, just like in the caves. (Ignore the air pockets on the ocean floor, this is an unrelated issue: MC-129625) Like with the caves, newly generated ocean does not have this issue.

Confirming the issue affects 18w20c, although seagrass in newly-loaded chunks is fine and generates normally. 

Also, to anyone wanting a temporary fix to this issue, you can use the fill command to replace the air with seagrass or water (though if you replace with seagrass it will put two 1-block high seagrasses on top of each other). 

There's a block limit to the bounds you can put on the fill command, but it should be something like this:

/fill 0 50 0 50 40 50 seagrass replace air  OR  /fill 0 50 0 50 40 50 water replace air

You'll have to do this over and over again, but it's better than nothing (especially since hostile mobs spawn in the air pockets). 

No, neither MC-696 nor MC-28440 describe the issue. (MC-696 does happen, but this is separate from that, and has nothing to do with hostile mobs). I have like 30 cats, all sitting in a pen outside my house, and several times I have gone back in my house (with no hostile mobs in the area) and one or more of the sitting cats teleports to me. It's very annoying, especially since this issue is co-occuring with MC-124740