I'd only seen this on a Reddit thread so I apologize if this is a repeat. 

If you turn off the Mars/Space Race win condition it doesn't actually turn off and the AI, or any human player, can still end the game by choosing that dialogue box option when the Mars Colony is completed. 

Playing a game recently and the following happened:

1) an AI triggered "the game will end next turn" dialogue box and it was because of the completion of the space race, I was frustrated because I'd turned that off.

2) then the game did NOT end which was a nice surprise, perhaps this was fixed!

3) 20+ turns later the game suddenly ends because of the completion of the space race?

I wonder if the bug was worked on but doesn't account for multiple AIs doing it so a second AI triggered it? It seems to me like entirely different alternative dialogue box choices need to be made for when this end game condition is turned off...

Thanks! Great game, love it, just needs more bug fixes