Whats wrong with AddTorque and compound colliders ?

[SnegCozine]

I make Rigidbody with compouded box colliders as childs and constraint everything except Y rotation

Have a c# script which apply AddTorque to rigidbody

public class Rotator : MonoBehaviour {

Rigidbody rb;

void Start () {
	rb = GetComponent<Rigidbody> ();	
}

void OnMouseDown (){
	rb.AddTorque (0,20f,0);
}

}

I apply addTorque and expect rigidbody will rotate around world-Y-axis.
But in some cases rotation is magicaly affected (See fig.)

Reproduced in 5.0, 5.3, 5.4, 5.5 Unity

Normaly worked in 4.6

Is it bug?

[SnegCozine]

Ok. Solution found. Need to reset inertiaTensorRotation like this Unity - Scripting API: Rigidbody.inertiaTensorRotation
and all perfectly work