message: Fix small logic issue with feature_set
diff: @@ -94,7 +94,7 @@ replace(const Feature & feat, float val)
  it->second = val;
  ++it;
  int start = it - features.begin();
  - int pos = 0;
  + int pos = start;
  /* Shift those to delete back to maintain sorted property. */
  int num_to_delete = 0;
  