[MC-138547] Opening a 1.12.2 world in 18w44a or newer causes terrain to regenerate

Opening a 1.12.2 world in the 18w44a snapshot causes the terrain to be regenerated, replacing already existing blocks (placed by player). This is how the world is supposed to look (screenshoted in 1.13.2):

And this is the world in 18w44a (loaded from a backup saved in 1.12.2):

Opening the world in 18w44a caused a crash before the world was loaded the first time:

---- Minecraft Crash Report ----
// Why did you do that?Time: 31.10.18 17:33
Description: Ticking block entity

java.lang.IllegalArgumentException: Cannot get property bog{name=enabled, clazz=class java.lang.Boolean, values=[true, false]} as it does not exist in Block{minecraft:stone}
	at bnf.c(SourceFile:95)
	at blz.a(SourceFile:138)
	at blz.Z_(SourceFile:129)
	at azt.n_(SourceFile:1068)
	at ua.n_(SourceFile:296)
	at net.minecraft.server.MinecraftServer.b(SourceFile:756)
	at net.minecraft.server.MinecraftServer.a(SourceFile:685)
	at dlv.a(SourceFile:128)
	at net.minecraft.server.MinecraftServer.run(SourceFile:573)
	at java.lang.Thread.run(Unknown Source)

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

-- Head --
Thread: Server thread
Stacktrace:
	at bnf.c(SourceFile:95)
	at blz.a(SourceFile:138)
	at blz.Z_(SourceFile:129)-- Block entity being ticked --

Details:
	Name: minecraft:hopper // blz
	Block: Block{minecraft:stone}
	Block location: World: (-385,6,321), Chunk: (at 15,0,1 in -25,20; contains blocks -400,0,320 to -385,255,335), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Block: Block{minecraft:stone}
	Block location: World: (-385,6,321), Chunk: (at 15,0,1 in -25,20; contains blocks -400,0,320 to -385,255,335), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)

Stacktrace:
	at azt.n_(SourceFile:1068)
	at ua.n_(SourceFile:296)

-- Affected level --
Details:
	Level name: hardcore
	All players: 0 total; []
	Chunk stats: ServerChunkCache: 2025
	Level seed: 2429879850955639764
	Level generator: ID 03 - amplified, ver 0. Features enabled: true
	Level generator options: {}
	Level spawn location: World: (-399,122,329), Chunk: (at 1,7,9 in -25,20; contains blocks -400,0,320 to -385,255,335), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 39884077 game time, 32408364 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 34931 (now: false), thunder time: 130706 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false

Stacktrace:
	at net.minecraft.server.MinecraftServer.b(SourceFile:756)
	at net.minecraft.server.MinecraftServer.a(SourceFile:685)
	at dlv.a(SourceFile:128)
	at net.minecraft.server.MinecraftServer.run(SourceFile:573)
	at java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
	Minecraft Version: 18w44a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_191, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 873526480 bytes (833 MB) / 1644167168 bytes (1568 MB) up to 3817865216 bytes (3641 MB)
	JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx4G
	Player Count: 0 / 8; []
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

And a second crash occurred after loading the world again, after a few seconds in game with the same cause

//EDIT 01.11.2018

A download of the world can be found here: https://www.dropbox.com/s/wrk5j2y5q92kh4t/World-1-12-2.zip

Note: Unnecessary chunks (chunks not near to the world spawn) have been removed with MCEdit.

The issue occured exactly as described above with the pruned world available for download, when loading it directly in 18w44a.