encode_value for objects

Hmm. Isn't it enough to provide an _encode and _decode method to allow objects to be en/decoded? I get this:

Cannot encode objects without an "encode_object" function in the codec. pgallery.pike:24: pgallery()->main(1,({"/home/neotron/src/pgallery/pgallery.pike"}))

The documentation states that the Codec in the master will be used if none is provided - well, it has:

mixed encode_object(object x) { if(x->_encode) return x->_encode(); error("Cannot encode objects yet.\n"); }

Am I missing something? Hmm. Ok, so it DOESN'T use the default codec in the master it seems. It works with:

encode_value(o, master()->Codec());

Documentation error, bug or something that is new in Pike 7.5?