Scenario Editor Researching Supplies Automatically?

I was just doing a quick test in the scenario editor and I found that if you load a scenario in Castle age with a civ that has access to supplies, the technology will already be researched when you enter the scenario.

This happens if you enter the scenario through a test or by loading it in single-player, and happens even if you start the scenario without a barracks and build one.

Does anyone know more about this?