- Fix apparent failures when calling ``pyramid.traversal.find_model(root,
  path)`` or ``pyramid.traversal.traverse(path)`` when ``path`` is
  (erroneously) a Unicode object. The user is meant to pass these APIs a
  string object, never a Unicode object.  In practice, however, users indeed
  pass Unicode.  Because the string that is passed must be ASCII encodeable,
  now, if they pass a Unicode object, its data is eagerly converted to an
  ASCII string rather than being passed along to downstream code as a
  convenience to the user and to prevent puzzling second-order failures from
  cropping up (all failures will occur within ``pyramid.traversal.traverse``
  rather than later down the line as the result of calling
  ``traversal_path``).