Assigned vehicles appear as idle while returning from tipping

Issue description

Vehicles assigned to a building appear as idle in the vehicle manager when they are returning from tipping their load, not idle.

Reproduction steps

Assign vehicles to a building, check their status in the vehicle manager when they are in transit and empty (click on the appropriate zZ counter until the camera focuses on them).

Game version and build number

v0.7.9 b495

Operating system

Windows

I had the same problem, which masked a huge throughput issue I had and seems pretty inconsistent.