Playing fire extinguish sound when undeads in rain/water at daytime

Whenever undeads like zombies or skeletons are in the rain at daytime, the fire extinguish sound is played from time to time. However, they are not set on fire.

What I expected to happen was...:
The zombies and skeletons are not affected by the daylight as they are "protected" by the rain.

What actually happened was...:
From time to time you can hear the fire extinguish sound, however none of the undeads are burning.

Steps to Reproduce:
1. Enter the command /toggledownfall to activate rain.
2. Set the time to day with /time set day
3. Place a group of zombies and/or skeletons.
4. Hear how the fire extinguish sound is played from time to time. However, none of the mobs are really burning.