I've put together a PR of backported bugfixes for an upcoming yt 3.3.3 release. Feel free to glance it over and give comments. The PR includes a couple dozen bugfixes merged over the last 1.5 months since our last bugfix release. It passes all the unit tests in py2 and py3, but fails several answer tests simply because of misalignment between the stable and dev api.
I was hoping to get this merged rather quickly so we can put out the release in the next day or so. This will be the stable version of yt that trident builds off of, and we're putting out the trident method paper on the arxiv this week with our first 1.0 release of the code.
Let me know if you have any questions or comments.