I think the patch you are thinking of is one that affected which way iOS saw the landscape orientations (I was the one who discovered it and showed how to fix it). That is now part of the delivered code for Xcode now.
In your Xcode project, did you make sure to indicate that it only allows the two landscape orientations?
What version of Xcode are you working with? They changed the interface a lot in Xcode 5.
In your Xcode project, click on the 'agkinterpreter' in the far left column. Then select the 'agk_interpreter' TARGET. In Xcode 4, this is under the project name. In Xcode 5, you click on the little 'agkinterpreter' in the left uppper corner of the big section in the middle. Then select 'agk_interpreter' from the Targets in the opened up list. Then select the 'General' tab/section. Scroll to 'Deployment Info'. In Xcode 4, there will be two sections, one for iPhone and one for iPad. In Xcode 5, you select one or the other by clicking on the 'iPhone' or 'iPad' tags under the 'Devices' dropdown selection (make sure that is set to 'universal'). Then make sure that only the to landscape modes are selected for both iPad and iPhone.
Then look in
this post for some other bits to do.
Also, make sure that the portrait default images you create are actually your landscape images rotated to portrait. That way, even if it starts in portrait, it looks like it is landscape and encourages the user to rotate the device.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master