built-in implementations that implement the interface (``repoze.bfg.traversal.ModelGraphTraverser``, and ``repoze.bfg.urldispatch.RoutesModelTraverser``) now expect the ``__call__`` method of an ITraverser to return 3 additional arguments: ``traversed``, ``virtual_root``, and ``virtual_root_path`` (the old contract was that the ``__call__`` method of an ITraverser returned; three arguments, the contract new is that it returns six). ``traversed`` will be a sequence of Unicode names that were traversed (including the virtual root path, if any) or ``None`` if no traversal was performed, ``virtual_root`` will be a model object representing the virtual root (or the physical root if traversal was not performed), and ``virtual_root_path`` will be a sequence representing the virtual root path (a sequence of Unicode names) or ``None`` if traversal was not performed. Six arguments are now returned from BFG ITraversers. They are returned in this order: ``context``, ``view_name``, ``subpath``, ``traversed``, ``virtual_root``, and ``virtual_root_path``. Places in the BFG code which called an ITraverser continue to accept a 3-argument return value, although BFG will generate and log a warning when one is encountered. - The request object now has the following attributes: ``traversed`` (the sequence of names traversed or ``None`` if traversal was not performed), ``virtual_root`` (the model object representing the virtual root, including the virtual root path if any), and ``virtual_root_path`` (the seuquence of names representing the virtual root path or ``None`` if traversal was not performed). - A new decorator named ``wsgiapp2`` was added to the ``repoze.bfg.wsgi`` module. This decorator performs the same function as ``repoze.bfg.wsgi.wsgiapp`` except it fixes up the ``SCRIPT_NAME``, and ``PATH_INFO`` environment values before invoking the WSGI subapplication. - The ``repoze.bfg.testing.DummyRequest`` object now has default attributes for ``traversed``, ``virtual_root``, and ``virtual_root_path``. - The RoutesModelTraverser now behaves more like the Routes "RoutesMiddleware" object when an element in the match dict is named ``path_info`` (usually when there's a pattern like ``http://foo/*path_info``). When this is the case, the ``PATH_INFO`` environment variable is set to the value in the match dict, and the ``SCRIPT_NAME`` is appended to with the prefix of the original ``PATH_INFO`` not including the value of the new variable. - The notfound debug now shows the traversed path, the virtual root, and the virtual root path too.