# File lib/uri/generic.rb, line 914
    def route_from(oth)
      # you can modify `rel', but can not `oth'.
      begin
        oth, rel = route_from0(oth)
      rescue
        raise $!.class, $!.message
      end
      if oth == rel
        return rel
      end

      rel.set_path(route_from_path(oth.path, self.path))
      if rel.path == './' && self.query
        # "./?foo" -> "?foo"
        rel.set_path('')
      end

      return rel
    end