Fixed #12649 - more helpful Unicode exceptions for CSRF migration helper script

            return self._content

        except AttributeError:

            fd = open(self.absolute_filename)

            try:

                content = fd.read().decode(TEMPLATE_ENCODING)

            except UnicodeDecodeError, e:

                message = '%s in %s' % (

                    e[4], self.absolute_filename.encode('UTF-8', 'ignore'))

                raise UnicodeDecodeError(*(e.args[:4] + (message,)))

            fd.close()

            self._content = content

            return content