World Seed reset to "0" after upgrade from one snapshot to another

If you built a slime farm before this snapshot it will no longer work once updated. My guess is the slime chunk is actually now positioned adjacent to where it used to be.

Description from MC-186137:

RandomSeed not converted to minecraft:dimention seed from the WordGenSettings resulting in seed 0 to all worlds from previous versions

RandomSeed value is not transfered to minecraft:overworld, minecraft:the_nether and minecraft:the_end seed from the WordGenSettings resulting in seed 0 to all worlds from previous versions. It creates odd chunk generations near the borders of newly generated chunks and other issues like that.