Trains behave weird with Loading Stations set to 'None'

Issue description

When there are station modules stet to 'None' behind a station module of the same type a longer train with the same type of wagons wont get filled by moving forward.

Reproduction steps

1. Build Loading Station with one module set to a specific product
2. Build Loading Station with the same module type (Bulk, ...) but set no specific product ('None')
3. Set up Unloading Station for the product from 1. and build a train route to pick up the product. Train must have more wagons than the number of station modules built in 1.
4. Not all wagons get filled with product.

Game version and build number

v0.7.1e b424

Operating system

Windows

No save file is attached, but the issue is most likely fixed, as we reworked the alignment logic significantly since this bug was reported.