Merge pull request #5241 from monster860/patch-1

Fix ChangeTurf permanently making obscured areas obscured for AI's

code/game/turfs/turf.dm

@@ -163,6 +163,7 @@
 	var/list/old_affecting_lights = affecting_lights
 	var/old_lighting_overlay = lighting_overlay
 	var/old_blueprint_data = blueprint_data
+	var/old_obscured = obscured
 
 	if(air_master)
 		air_master.remove_from_active(src)
@@ -185,6 +186,8 @@
 			lighting_build_overlays()
 		else
 			lighting_clear_overlays()
+	
+	obscured = old_obscured
 
 	return W