The bug

Patrols won't spawn near to a village created by a player. They will spawn only near to naturally generated villages. I don't think that this is intended, as pillagers shouldn't make the distinction between villages that were created by the player or not : they should focus on both.

How to reproduce

• Create a default world and create a village (using doors and villager spawn eggs) in a plain biome without any naturally village generated (example of location : seed -5046987773477302630 ; coordinates -1000 ~ 2000)
• Enter the command /time add 64d
• Set the gamerule doMobLoot to false
• Place a repeat command block that kill everything beside player, villagers, pillagers and items
• Give stacks of carrots to villagers
• They'll start breeding, showing that a village was created
• Patrols won't spawn