Scripted prim movement rendering broken with update?

Drop this script into a child prim (I used 2 linked cubes):

default
{
    state_entry()
    {
        llSetTimerEvent(3);
    }

    timer()
    {
        llSetRot(llGetRot() * llAxisAngle2Rot(<0, 0, 1>, PI / 8.0));
    }
}

Here's what I see.

* Object rezzed in world - prim rotation looks smooth, i.e. what I'd expect to see.
* Object rezzed in world and selected in the edit menu - prim snaps to final rotation
* Object worn as attachment - not sure what's happening, but it looks like the prim is turning through the 'bigger' arc, so it ends up in the right position, I think, but the rotation looks much bigger. This is more readily visible if the child prim is long, flexi, and starts out laying on its side (so the local Z axis is horizontal, which increases the flexi movement from the rotation).

I bug reported this, but if anyone can confirm that they see it too, that would be good. I don't think this is an issue with my graphics card drivers, but you never know

Edit: Wait, the attachment case will be different because the root prim is now the av. Never mind. But the selected/unselected difference... has that always been there, or is that new?

I have some attachment products with moving flexi prims that are moving differently now, and I'm trying to narrow down the test case.