It's been merged into the main kernel (i.e. the one maintained by Linus). Distributions can apply their own patches against the main kernel, which Debian did for RISC-V support. They don't have to apply the patches anymore.
Functionality wise, what's been merged is only a subset.
ABIs have changed after we did this. We get the first long-term stable ABI with 4.15 kernel and glibc 2.27 (hopefully). At that point Fedora, Debian, and others can reboot efforts.
That was great work and it made RISC-V look that much more viable to me. To think that thousands of programs are ready to go whenever the hardware arrives is really amazing. It's unfortunate that some of it has to be repeated after the ABI changes, but that seems a small price to pay in the grand scheme of things. But then I'm not the one who did it or has to redo it ;-) Anyway, great job guys!
Since the status log includes the patch request and news about it, I think none. It seems originated from the combined efforts of the RISC-V community at large and supported by the distribution.
Also, how is this different to: https://wiki.debian.org/RISC-V ?