object ignores collision when setting scale to negative

when setting the scale to negative the object ignores collisions

this is related to #246
setting the x scale to negative is a way to flip the whole object and children easely from left to right
here is the function to add as a startupsystem:

`
fn test(
mut commands : Commands,

){

let object_width = 10.0;
let object_height = 25.0;

commands.spawn_empty(

)

.insert(

Collider::cuboid(object_width, object_height)
)
.insert(RigidBody::Dynamic)
.insert(LockedAxes::ROTATION_LOCKED)
.insert(Transform::from_xyz(-50.,200.,0.))
.insert(GlobalTransform::default())

;

let mut other_object_transform = Transform::from_xyz(0.,200.,0.);
other_object_transform.scale.x = -1.;
commands.spawn_empty(

)

.insert(

Collider::cuboid(object_width, object_height)
)
.insert(RigidBody::Dynamic)
.insert(LockedAxes::ROTATION_LOCKED)

.insert(other_object_transform)
.insert(GlobalTransform::default())

;

let ground_size = 500.0;
let ground_height = 30.0;

let map_ground = commands.spawn_empty()
.insert(

Collider::cuboid(ground_size, ground_height)
)
.insert(RigidBody::Fixed)
.id();

let mut camera_transform = Transform::from_scale(Vec3::new(0.5,0.5,1.));
camera_transform.translation.z = 900.;

let camera_ent = commands.spawn(
Camera2dBundle::default())
.insert(camera_transform)
.insert(PlayerCamera)
.id()

;

}

`
what i expected the two objects fall and collide with the plattform

what happend the modified object falls though the plattform