Excavators in a zone with no fuel station do not refuel if one exists elsewhere

Issue description

I have a logistical zone set up called "Causeway" that contains a mining tower with two excavators and three trucks, plus another 3 trucks assigned to the zone or another container in the zone . There is a diesel container inside the logistical zone that has diesel in it (and the trucks happily refuel there). The logistical zone has no fuel station and no fuel station is assigned to export to the tower.

Expected behavior: Excavators make the short trip to the diesel container and refuel.
Actual behavior: Excavators continue mining until they run out of fuel (around 0080-August in the attached save).
Notes: If I delete the fuel station from the Default zone, the excavators behave correctly and refuel. This suggests the check on whether excavators need to refuel themselves is using global logic rather than the conditions that actually prevail in the logistical zone (i.e. is my tower served by a fuel truck)

Reproduction steps

1. Load attached save.
2. Watch excavators refuse to refuel in the nearby diesel container despite it being in the logistical zone and run out of fuel.
3. Reload attached save.
4. Delete Fuel Station near Iron Mine (outside of the logistical zone).
5. Watch excavators figure out they can refuel in the container and continue their work.

Game version and build number

v0.7.4 (b441)

Operating system

Windows

Attachments

Excavator Fuel Issue.save

Files not imported: Excavator Fuel Issue.save

It's true this can be worked around by simply assigning the Fuel Station to have an Export route to the tower the Excavators are assigned to (and in this case that works okay as the Excavators aren't that far away), but if this was on the other end of the island and I was shipping diesel in by train I wouldn't want to have to waste a truck on a fuel station just to service 2 Excavators that can happily refuel at a container. Nor would I want my main Fuel Station trucks to drive halfway across the island.

I can confirm this issue in 0.7.7
Exactly as described by tjayharvey

I also have the same issue in 0.7.7 (b470)

This was fixed as part of v0.7.9. Thank you!