Minecraft wiki entry for Development_versions, associated text: Vindicators are no longer part of patrols.
Doubled the minimum time to spawn from 5 minutes to 10–11 minutes.
Patrols now follow hostile mob spawning rules.
Patrols no longer spawn if the block light level disallows monster spawning.
Patrols are now allowed to spawn in any biome except mushroom biomes.