This doesn't work and hasn't been actively developed for over 2 years. The master branch is for functional code, so this should be either moved to a (private) branch for continued development or removed entirely if it's a dead pile of code.
Yeah that patch is why this ticket exists. How/why are you using this, what downstream modifications do you have, literally nothing about this makes sense. This is the functional equivalent of using a beta API.
Turns out the render2/region.c code is also being used by Eina_Tiler (for region_new function). Before this ticket happens, the region code will likely need to be relocated (perhaps made into Eina_Region??)