Added graceful handling of the directory structure changing during a 'walk'.
Added graceful handling of the directory structure changing during a 'walk'.

git-svn-id: 74b2def6592cf29d88d1a5d33b5c4a2732d8507c@567 67cdc799-7952-0410-af00-57a81ceafa0f

pombreda/pyfilesystem-4