As for the bug, it's a rather annoying one. When you "acquire" a city from someone else (or vice versa), the way the game handles it is by destroying the existing city (first saving all relevant details about it), and then recreating it for the new owning player (and re-assigning all relevant details). Anyone thinking ahead has probably already guessed the problem.
But to spell it out, inbetween the "destroying" and "recreating", it checks to make sure all the units on the square are valid. Well, a water unit on a square that currently doesn't have a city (or fort) obviously isn't valid. And since it's inbetween the destroying/recreating stages, the game doesn't consider the square to have a city. So it bumps all the water units.
Unfortuntely I don't think I can change the order in which it does the checks. Most of the time, it should bump units that shouldn't be on the square a city is being created. The simplest solution would be to make City Ruins a valid square for water units (they are created inbetween the destroying/recreating part). But while a fairly minor change, it's still going to affect other areas beyond just fixing this issue.
Bh
I thought I've seen everything when it comes to drafting, but no...
I've created a colony and one of those cities is founded on copper, so
the AI won't draft warriors. Guess drafting goes before anything else.
Could you place a fort on the tile between the destruction of the old city and the creation of the new city. The fort could harbour the sea/air units and will be removed once the new city is placed there.
Unfortuntely I don't think I can change the order in which it does the checks. Most of the time, it should bump units that shouldn't be on the square a city is being created. The simplest solution would be to make City Ruins a valid square for water units (they are created inbetween the destroying/recreating part). But while a fairly minor change, it's still going to affect other areas beyond just fixing this issue.
Hmm, that's not a bad idea. I think that should work, as long as I add it after it's been destroyed, but before it's about to be recreated.
Bh
@Aquatic: Just a comment about that save you posted (unrelated to the bug)... You've got a bunch of spies lining your borders, which I assume are there to try and catch incoming spies? If so, they won't be effective. Spies can use enemy roads/railroads. Therefore, it is very unlikely that the enemy spies will end their turns just inside your borders. And spy detection only works on the tile they are sitting on at the beginning of their turn (so the end of their last turn). They don't get detected as they are moving.
Bh
Suggested workaround:
Could you place a fort on the tile between the destruction of the old city and the creation of the new city. The fort could harbour the sea/air units and will be removed once the new city is placed there.
Or will there always be a check for units on the exact wrong moment?
Hmm, that's not a bad idea. I think that should work, as long as I add it after it's been destroyed, but before it's about to be recreated.
Bh
If I download this patch will I be able to play online? or will it mess it up?