lib/astar: report final queue length

lib/astar.py

@@ -27,6 +27,7 @@ def search(start, is_goal, neighbors, heuristic=None):
 
         if is_goal(this):
             print("astar: visited", len(done), "nodes")
+            print("astar: pending", len(q), "nodes")
             # reconsruct the path
             n = this
             path = []