How to Replicate:

1. Check if "Friendly Fire" is off, check MCPE-172008
2. Collect a bow, a punch II book, arrows and an anvil 
3. Join them in the anvil
4. Change to survival
5. Self hit yourself with the bow.
6. You are affected by the Punch enchant

Expected Results:

The Punch effect would be canceled and the arrow would go through the player.

Oh and I almost died because I fell my tower with this bug