Some mobs still deal damage to other mobs in Peaceful mode

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Your report does not contain enough information to understand or reproduce the problem.
To help in confirming your report, please add the following information to the Description, as shown here:

Steps to Reproduce:
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Please review the Bug Tracker Guidelines before creating additional bug reports.

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1. Load a world in Peaceful Mode (Can be either Creative or Survival) and allow some time for mobs to spawn

2. Find a Wolf or Fox but do not interact with it in any way. Just be sure to stay within its spawn region 

3. Wait for a Sheep or Chicken to spawn in the same area as the mobs mentioned above

4. When a Wolf sees a Sheep, its eyes will turn red as if it was attacked by the player then chase and jump on the Sheep until it dies

5. If a Fox sees a Chicken, the Fox will attack the Chicken until it dies then run away, taking the dropped piece of Raw Chicken with it

What should be seen is the opposite where Peaceful Mode is what it's meant to be, Peaceful with no hostility whatsoever 

This is working as intended, see MC-141141.