if self.asvar is None:
                        # Re-raise the original exception, not the one with
                        # the path relative to the project. This makes a
                        # better error message.
                        raise e
            else:
                if self.asvar is None:
                    raise e

        if self.asvar:
            context[self.asvar] = url
            return ''
        else:
            return url