also prevent updating seen tiles when checking vision

squirrelbattle/interfaces.py

@@ -197,9 +197,11 @@ class Map:
     def is_visible_from(self, starty: int, startx: int, desty: int, destx: int,
                         max_range: int) -> bool:
         oldvisibility = deepcopy(self.visibility)
+        oldseen = deepcopy(self.seen_tiles)
         self.compute_visibility(starty, startx, max_range)
         result = self.visibility[desty][destx]
         self.visibility = oldvisibility
+        self.seen_tiles = oldseen
         return result
 
     def compute_visibility(self, y: int, x: int, max_range: int) -> None: