- It is no longer possible to pass an environ dictionary directly to
  ``pyramid.traversal.ResourceTreeTraverser.__call__`` (aka
  ``ModelGraphTraverser.__call__``).  Instead, you must pass a request
  object.  Passing an environment instead of a request has generated a
  deprecation warning since Pyramid 1.1.

- Pyramid will no longer work properly if you use the
  ``webob.request.LegacyRequest`` as a request factory.  Instances of the
  LegacyRequest class have a ``request.path_info`` which return a string.
  This Pyramid release assumes that ``request.path_info`` will
  unconditionally be Unicode.

- Pyramid now requires WebOb 1.2b3+ (the prior Pyramid release only relied on
  1.2dev+).  This is to ensure that we obtain a version of WebOb that returns
  ``request.path_info`` as text.