For some reason, chickens spawn in Nether. I've met a few chickens in Nether. I am plaing in super-flat world.
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Thank you for your report!
However, this issue is Working as Intended.
Chickens can be found in the Nether as a result of being spawned with chicken jockeys.
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well, zombie pigman jockeys do exist.
Please do not mark unreleased versions as affected.
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