They don't do it since v.2.6 already. You can (potentially) establish an embassy to a player with "NoDiplomacy" effect, you just can't meet. So ULR_EXECUTED is unused except maybe by a script.
We should make it clear from help and code comments (server/diplomats.c) that barbarians won't execute the diplomat. We might bring back the "oh, I forgot I can't do it to barbarians!" gameplay with a script callback if we have a way to make AI diplomats not fumble this way too often.
They don't do it since v.2.6 already. You can (potentially) establish an embassy to a player with "NoDiplomacy" effect, you just can't meet. So ULR_EXECUTED is unused except maybe by a script.
We should make it clear from help and code comments (server/diplomats.c) that barbarians won't execute the diplomat. We might bring back the "oh, I forgot I can't do it to barbarians!" gameplay with a script callback if we have a way to make AI diplomats not fumble this way too often.