I imagine you would never see this bug in a regular game, but it's a bug nonetheless.
I was fooling around with fire-tuner, and gave my starting Jaguar (playing as aztec's) 5000 xp. It was able to get every promotion possible, with some xp still up my sleeve.
I killed a barbarian unit, and sustained 2 damage. As a Jaguar though, I regained 2 health. For those unable to do the math, I was back to full health. But because I had for a brief moment been under full health, the "heal" promotion was made to me, and the flag for "Promote Unit" was raised. But the "heal" promotion wasn't available anymore, as I was once again at full health. I was not able to continue the game due to the default rules required me to promote my unit...
Hey, I was only fooling around, so no biggy. But it *could* be possible that a Jaguar could be upgraded throughout a game till mech inf, and get all the promotions along the way. I guess if that did happen, you could always continue the game by deleting the unit... but that would suck.
I was fooling around with fire-tuner, and gave my starting Jaguar (playing as aztec's) 5000 xp. It was able to get every promotion possible, with some xp still up my sleeve.

I killed a barbarian unit, and sustained 2 damage. As a Jaguar though, I regained 2 health. For those unable to do the math, I was back to full health. But because I had for a brief moment been under full health, the "heal" promotion was made to me, and the flag for "Promote Unit" was raised. But the "heal" promotion wasn't available anymore, as I was once again at full health. I was not able to continue the game due to the default rules required me to promote my unit...
Hey, I was only fooling around, so no biggy. But it *could* be possible that a Jaguar could be upgraded throughout a game till mech inf, and get all the promotions along the way. I guess if that did happen, you could always continue the game by deleting the unit... but that would suck.