Merge pull request #7454 from VOREStation/upstream-merge-7018

[MIRROR] Space spaced through open space looks like space

code/modules/multiz/turf.dm

@@ -82,8 +82,13 @@
 /turf/simulated/open/update_icon()
 	cut_overlays() // Edit - Overlays are being crashy when modified.
 	update_icon_edge()// Add - Get grass into open spaces and whatnot.
-	var/turf/below = GetBelow(src)
 	if(below)
+		// Skybox lives on its own plane, if we don't set it to see that, then open space tiles over true space tiles see white nothingness below
+		if(is_space())
+			plane = SPACE_PLANE
+		else
+			plane = OPENSPACE_PLANE + src.z
+
 		var/below_is_open = isopenspace(below)
 
 		if(below_is_open)