188.8.131.52 Beta, 184.108.40.206 Beta, 220.127.116.11 Beta, 18.104.22.168 Beta, 1.11.0, 1.11.1, 1.11.2, 1.11.3, 1.11.4, 1.12.1, 1.12.0
If a villager is linked to a bed (can sleep in it), it will not unlink from that bed if it goes to another dimension, such as the nether or end. Or to the overworld from the nether.
This basically makes it so that bed cannot be claimed by another villager, preventing villagers from breeding.
This is also unlike previous mechanics using doors, where a villager would take up part of the cap, and then be take out of the cap when they go to another dimension.
How to reproduce:
1. Summon a villager, and have them pair with a bed.
2. Send that villager to the nether
3. Spawn another villager and you will see they cannot link to the original bed. You need to place another bed, or destroy and replace the original.
Villager would un-link from bed once they have gone to another dimension, allowing a new villager to claim their bed.
This bug has fairly serious implications for villager breeders, and village tech in general.