scanner: handle search failure

python/tools/scanner.py

@@ -114,6 +114,7 @@ def step(cur_h, cur_depth):
 
 def nextstep(cur_h, cur_depth, ok, nodes, arc=None, lines=[]):
     global done, all_nodes
+    if nodes:
         if arc:
             arc.remove()
             del arc
@@ -128,6 +129,8 @@ def nextstep(cur_h, cur_depth, ok, nodes, arc=None, lines=[]):
                 new_h = InfoHash(cur_h.toString());
                 new_h.setBit(b, 1);
                 step(new_h, b+1);
+    else:
+        print("step done with no nodes", ok, cur_h.toString().decode())
     done -= 1
 
 run = True