[bug?] Slope under bridge

[z9999]

In simutrans 102.0, we could build artificial slopes under bridge.
So that, we could build a tunnel for example.

But in current nightly version, we can't build artificial slopes under bridge.
Is this the intended behavior or a bug ? Thanks.

[Dwachs]

Imho, this is intentional. The responsible check also forbids to built underground slopes that would collide with the surface.