A big problem in the new Deep Dark biome

Although the deep dark just came out in an experimental snapshot and many things may change there is a big issue. Although no mobs spawn in that biome bats somehow find their way into that biome from a cave system and see off the shriekers causing the warden to spawn. I have experienced this problem quite a few times and although I was as sneaky as possible there whould always be a bat that would notify the warden. A solution to that could be either make bats give zero vibrations or either make them not wanting to go near the deep dark.