As I said, the Aztecs will attack my city, which turns barbarian and then they capture it right after that with normal units. The city has Walls, yet in this case there are no units that can see invisible units very well. But it also worked for them with high disguise and carmo visibility on my site.
They attack if you hit end of turn; the city in question is the island city in the north, just north of my capital.
It wasn't the latest SVN build, but it was only 3 SVN versions ago or so.
Probably the same underlaying problem: Bandit Raiders can attack my units inside a city, eventhough I have 100% Defense and Walls built (can't invade above 60%).
That particular situation may have been a little too tough to figure out all the details on because its a very detailed game with a lot going on and it makes it hard to catch in the code what's happening there. Also hard to open WB for some further analysis.
However, I checked the code regarding HN units that can attack cities, looking for why they might be getting around the minimum defense to enter levels. Indeed I found a logic flaw there that would only ask if the check should be made if the team that owns the unit was at war with the team that owns the city. This would thus be ignored if the teams weren't at war, even though the ruffian should be attacking and thus be required to check against that minimum entry level.
So I made it check the APPARENT team of the unit (in the case of HN, this means it comes up with a Barbarian team owner 'apparently'.) This fixed the issue but it doesn't resolve your situation. I think it has to do with the city already being under the minimum entry level.
You were reporting, in your first post, a bug that isn't a bug at all but a new feature. When HN units that CAN capture a city do so, they capture it for the barbarian player, which can indeed pave the way for your other units to come back behind them and capture the city for yourself.
It's tough to pull off, harder now that I've fixed the minimum defense to enter issue. Ruffians and Strike Teams are generally not as strong against a city as conventional war units, particularly when you don't have much in the way of any ability to tear down the defenses. Of course, you can have your HN units capture a bunch of rams or other siege weapons - they will be captured as HN and you can keep them that way unless they ever enter your territory! But it can be an effective method of stealing a city from a player without going to war with them.
The AI isn't fully trained on making this an actual effort but its nice to see it can be clever enough to pull it off now and then.
I'll have a dll that fixes the no entry regarding HN units committed today.