MAJOR EDIT: As it turns out, the player shooting anywhere elicits this graphical glitch... again, just like in 15w31a. Fix pls dinnerbone

When a player tries to shoot between the gap between horizontal end rods (check screenshot) the arrow graphically stops in between them, as if the end rods are full blocks. However, it continues to go straight through on the server side, and will proceed to hit a mob, or stick in the ground.

Procedure to recreate:
1. Set up some end rods, preferably at eye level (though that doesn't matter) like in the screenshot below.
2. Summon a mob that will be past the end rods, so the end rods are in between you and the mob.
3. Shoot the mob, through the end rods. Notice how the arrow graphically stops and goes towards the ground, however, if you aimed properly, the mob will take damage.