This is one of those things that once known is so obvious it seems impossible for it to have existed so long but it has.
Anyone interested can try this experiment
Place 6 multi hex buildings spaced a few hexes apart
that have no part of the building in the hex you clicked on to place them
after you are done move your cursor over those hexes and you should see paved road reported
Now place map editor page one clear terrain on those registration hexes.. that's the clear terrain that is level zero
All the buildings should be gone
Now, look at the mini-map. You should still see the shape of where they were
Now change to winter ( this assumes you started the experiment in summer )
Pass your cursor over the area you placed those buildings hex by hex and every time you find one that reports paved road click on it with the clear terrain snow
You should see something like this............
What I found is why some of these older scenarios and probably the newer ones too that show strange residual paved road is because editing had been done that did not clear down all hexes that building was placed in and this is what we need to investigate in the code. Why an empty registration hex places a paved hex and why paved hexes are left behind when the building is removed when only the registration hex is cleared
SO........
Please note when building a map in case the cause of this cannot be found..... when you change your mind about the placement of a multi hex building you MUST clear down the entire area the building had been NOT just the registration hex
As well be aware that even if you place a multi hex building that DOES have a building in the registration hex and then you remove it by placing clear terrain in the registration hex
ANY HEX THAT BUILDING HAD OCCUPIED WILL REPORT PAVED ROAD.
So any "change of mind" when it comes to placing multi hex buildings EVERY hex they had occupied MUST be cleared using page one clear terrain to remove all traces of the paved road bug otherwise it will report being paved road