[0.13.1] Held items do not move along with the arm

Items held in hand do not move along with the player's crouching or punching animations, remaining at the player's side and bobbing as if the player were standing motionless.
Punching animations in first-person view are normal, the issue is only visible in third-person or externally (via other players).

Affects 0.13.1, not 0.13.0 as is given in the "affects version/s" field. Arm swinging (walking, sprinting, flying) animations are properly synchronized with the held item.