lua func "place_building_in_region" not work for mines

[hessenfarmer]

while creating a new scenario I found out that the lua function "place_building_in_region" does not work for mines.
This is from my perspective due to the function does not take into account "mine" construction lots when evaluating the sutability of a lot for the building.
Effect was:
while trying to place a mine to a specific field it failed with a "no space" message in messages window.
while trying to place it to a region it choose a normal building lot instead of a mine building lot (which isn't possible in normal building mode)

[GunChleoc (gunchleoc)]

Fixed in build20-rc1