no_routing_over_overcrowded causes unhappiness in separate network

[ceeac]

In the attached save, there are two separate passenger networks: a northern one and a southern one.
If a stop in the southern network is overcrowded, this will cause unhappy passengers to be logged in the southern network (this is expected).
However, unhappy passengers will also be logged in the northern network even though it has no overcrowded stops. This is counter-intuitive, and misleading in multi-player games because an overcrowded network of another player can cause orange halt statuses in your own network even though your own network works fine.