Comment 2 for bug 834571

The bug is actually in the lenses themselves.

Unity has a hack to workaround the issue (introduced by bzr revision 1405.1.5):

In plugins/unityshell/src/LensView.cpp:

  Categories::Ptr categories = lens_->categories;
  if (category.index + 1 == categories->count())
  {
    lens_->Search("---");
    lens_->Search("");
  }