Endpoint: /album/<album_id>/cover/<photo_id>/update.json

        Update the cover photo of an album.
        Returns the updated album object.

def cover_update(self, album, photo, **kwds):
        """
        Endpoint: /album/<album_id>/cover/<photo_id>/update.json

        Update the cover photo of an album.
        Returns the updated album object.
        """
        result = self._client.post("/album/%s/cover/%s/update.json" %
                                   (self._extract_id(album),
                                    self._extract_id(photo)),
                                   **kwds)["result"]

        # API currently doesn't return the updated album
        # (frontend issue #1369)
        if isinstance(result, bool): # pragma: no cover
            result = self._client.get("/album/%s/view.json" %
                                      self._extract_id(album))["result"]

        return Album(self._client, result)