ArcRotateCamera, Unable to undo "setTarget(mesh)" without moving mesh first

Hi guys, i notised that if you use arcRotateCamera and setTarget(mesh) you're unable to unlock the target, e.g setTarget(mesh.position.clone()); without updating the mesh's position first,

i'm using 2.5, but it is also available in the PG;

// Press any key to setTarget(sphere), press again to setTarget(sphere.position.clone()), try to pan using the left mouse button, you're still stuck, uncomment line 33 ( sphere.position.x += 0.00000001;), do it again and now you can pan..
Example; http://www.babylonjs-playground.com/#WHMIR#0