Reverse order slices are found, fix bugs

game.py

@@ -211,19 +211,17 @@ class MCWorld:
 
         return False
 
-    def find_sand_slice(self, center, distance, skip_to=(0, 0)):
+    def find_sand_slice(self, center, distance, bad_slices=[]):
         # returns the centre coord of the next 5x5x1 slice that still has
         # diggable sand in it. lower slices are only valid if there's an
         # adjacent slice farther at the same level. this should ensure an
         # upside down pyramid gets excavated so the edges are still climbable
-        skip_vertical, skip_spiral = skip_to
-
-        for v in count(skip_vertical):
+        for v in count():
             peak = utils.padd(center, (0, 20-v, 0))
 
+            slices = []
             layer = 0
-            start_step = skip_spiral if v == skip_vertical else 0
-            for step in count(start_step):
+            for step in count():
                 offset = utils.spiral(step)
                 layer = max(layer, *offset)
                 offset = utils.pmul(offset, 3)
@@ -233,10 +231,12 @@ class MCWorld:
                 if utils.phyp(center, check) >= distance:
                     break
 
-                if self.check_sand_slice(check):
-                    return (v-1, step+1), check
+                if self.check_sand_slice(check) and check not in bad_slices:
+                    slices.append(check)
 
-            if v > 40:
+            if len(slices):
+                return slices[-1]
+            elif v > 40:
                 return None, None