What is the code on the github? is it the latest community edition 126.96.36.199 or something else?
No, this is what will come after 1.9 - version 2.0. You can find more information here.
It is still in the process of development and if you're merchant, don't concern yourself with that for now. In the autumn there should be beta for merchants and only then you should try it.
But if you're a developer, then it makes sense to give it a look right now to see what will come and what you will have to do to prepare your extensions for it.
For magento 1.9.x community edition you can check it out here https://github.com/engineyard/magento-ce-1.9