upgrade to UUs in patch?

[Lester]

according to the patch read-me, civ-specific units are now part of the normal unit upgrade chain.

But in my games this doesn't seem to be the case. I'm playing the Chinese, and my horsemen won't upgrade to riders. Both horsemen and riders appear in the build box, and horsemen in barrack cities just won't upgrade (yes I have iron, horses, gold etc). and in the civlopedia it now states that horsemen upgrade straight to cavalry. whats the story here?

cheers
lester