"or I will break our alliance" diplomacy option doesn't do anything

[floralpond]

Description:

Originally Reported by Porfirogeneta in discord, there seems to be basically no way to break an alliance without declaring war. There is an option in diplomacy to say "do xyz or I will break our alliance", but if they refuse, then the alliance is not actually broken.

Expected behavior: Should be able to break an alliance via diplomacy using the "or I will break the alliance" option.

Actual behavior: An alliance seems to be automatically formed right after a refusal of the "or I will break the alliance" option.

Game version:

current main branch + FUN

Steps to reproduce:

cant_break_alliance.zip

1. Use attached save file which has an alliance already created between red (player) and purple (computer AI).
2. Diplomacy dialog option is already set to ask for votes "or I'll break our alliance", no need to do anything there.
3. End turn
4. Purple should refuse the deal.
5. The very next message says that Purple and Red have formed an alliance
6. Open up the diplomacy page and observe that purple and red still have an alliance, despite the "or I'll break our alliance" refusal

Additional information:

[Matt-Caspermeyer]

This will most likely need to fixed in the AI overhaul in V1.6, because the current logic is for the AI to refuse any contract with OR in it.