Horses only spawn and breed mature (also unable to mount certain horses)

Well, the title is pretty self explanatory. I'm just very confused by the horses right now in 14w29a. Firstly, no immature horses ever spawn from eggs or from breeding. Secondly, as per MC-62041, when the horse SHOULD continue accepting food to increase the chances of being tamed, they simply accept no food. Thirdly, sometimes I can mount a horse to tame it, but sometimes when you right click, your camera angle is changed but nothing else happens.

There's just a lot going on here, and I'm not going to be able to explain it all very clearly.

Just open up 14w29a, and spend a bunch of time messing around with horses and all the items related to horses to find all the details.