Returns a pathspec for an aff4 object even if there is none stored.

def real_pathspec(self):
    """Returns a pathspec for an aff4 object even if there is none stored."""
    pathspec = self.Get(self.Schema.PATHSPEC)

    stripped_components = []
    parent = self

    # TODO(user): this code is potentially slow due to multiple separate
    # aff4.FACTORY.Open() calls. OTOH the loop below is executed very rarely -
    # only when we deal with deep files that got fetched alone and then
    # one of the directories in their path gets updated.
    while not pathspec and len(parent.urn.Split()) > 1:
      # We try to recurse up the tree to get a real pathspec.
      # These directories are created automatically without pathspecs when a
      # deep directory is listed without listing the parents.
      # Note /fs/os or /fs/tsk won't be updateable so we will raise IOError
      # if we try.
      stripped_components.append(parent.urn.Basename())
      pathspec = parent.Get(parent.Schema.PATHSPEC)
      parent = FACTORY.Open(parent.urn.Dirname(), token=self.token)

    if pathspec:
      if stripped_components:
        # We stripped pieces of the URL, time to add them back.
        new_path = utils.JoinPath(*reversed(stripped_components[:-1]))
        pathspec.Append(
            rdf_paths.PathSpec(path=new_path, pathtype=pathspec.last.pathtype))
    else:
      raise IOError("Item has no pathspec.")

    return pathspec