https://minecraft.net/en-us/article/minecraft-snapshot-17w18a
We're getting close to releasing 1.12 now, this weeks snapshot brings us even
more bug fixes, some optimisations, and a couple of new Advancements.
Changes in snapshot 17w18a
Added new advancements for taming and breeding animals
Had some serious words with the Narrator, it should work for more people
now
Changed the levitate advancement to 50 vertical blocks
Changed the sniper duel advancement to horizontal distance
Re-introduced announcements to chat when someone earns an achievement
Added new gamerule "announceAdvancements", defaults to true
Changed some map colours around again
Added a new /reload command to reload advancements & loot tables from disk
Technical: Some optimisations to the recipe book
Technical: Optimized error conditions in command blocks
Technical: Added "tick", "tame_animal" and "breed_animal" advancement
triggers
Technical: Distance predicates in advancements now support: x, y, z,
horizontal and absolute distance checking
Technical: Added "announce_to_chat" and "show_toast" booleans to the
display info for advancements (both default true)
Technical: Advancement loading is now strict json
Fixed bug MC-113374 - Map colour palette changed (brown shade?)
Fixed bug MC-114966 - Advancements overlap other advancements
Fixed bug MC-115025 - Clicking on recipe or on book to close crafting
help additionally clicks in inventory
Fixed bug MC-115323 - Parrots spawn rarely in Jungle
Fixed bug MC-115577 - Parrot play the flapping wings(fly) sound, when
player push it
Fixed bug MC-115774 - Parrots still make sounds when they are on player
shoulder and Silent:1b
Fixed bug MC-115810 - Custom resourcepack added sounds not playing
Fixed bug MC-115902 - Flying parrots will not avoid lava
Fixed bug MC-116482 - The server.properties file still has
announce-player-achievements
Fixed bug MC-116498 - You can't place ladders on the back of stairs
Fixed bug MC-116515 - Placing a torch on a wall with a fence gate
underneath causes crash
Fixed bug MC-116534 - Pressing "Showing craftable" sometimes doesn't show
any recipes
Fixed bug MC-116537 - Stopping jukebox music while a sitting parrot is
dancing occasionally causes the parrot's entire upper body to be misplaced.
Fixed bug MC-116574 - "showing craftable" option has several issues
Fixed bug MC-116586 - Items in crafting grid disappear if the inventory
is not properly closed
Fixed bug MC-116670 - No toast is shown for first advancement made
Fixed bug MC-116675 - Debug messages are printed in log when levitating
Fixed bug MC-116713 - Creating new world with same name crashes with
NullPointerException
Added some new bugs!