[BUG] Upgrading Caravel to Destroyer

[caracarnn]

In my last game I upgrades my caravel with +2 vision to a destroyer and got a +3 vision also. I believe both these units start with these features but now I had a destroyed with +5 vision which feels abit bisarre...

 

[Grunthex]

Unit-specific promotions aren't being removed on upgrade of any sort.

Pikemen->Riflemen keep +100% bonus vs mounted.
Scout->Archer (via ruins) keeps no terrain penalty (even as you upgrade it all the way to mech inf)
Artillery->Rocket Artillery keeps the "must set up before fire" penalty.
Ottoman Janissaries keep their "heal when killing something"

The list is endless. It's not good.

 

[Rub'Rum]

Artillery->Rocket Artillery keeps the "must set up before fire" penalty.

This is particularly annoying, hehe.