For sake of reference, even with that PR, all seems pretty broken still:
1) Child jobs are not waiting anymore for parents to go in certain cases - still to bisect, but i believe this is a showoff from two different bugs in two different code parts e.g. https://openqa.suse.de/tests/1917358
2) Stale jobs in running state forever - In few days of having this in production, we are having back bugs that were actually addressed in the previous scheduler logics, that had to cope with production loads ( maybe we did simplified maybe too much here ? ) see for e.g. https://openqa.suse.de/tests/1925778 but we had plenty of them with ' State: running finished 3 days ago ( 00:03 minutes ) ' or similar.
3) Having a separated way to represent the cluster is a bit confusing now - we have settings page that show something that is not coherent what the scheduler is actually considering, and this makes things to debug even more messy, because you see something, scheduler does another, so from my point this is a big -1 as makes things a lot counterintuitive (just my opinion).
4) Tests are kinda bended to make them go successfully towards new scheduler logic, which makes me wonder if this is working as it is expected, as the core logic is not covered by unit tests.
For me, IMHO this is kinda a no-go at this point.