I think we are misunderstanding each other regarding our goals here :)

I'm not trying to test against other Python implementations or versions of CPython itself but rather "flush out" reproducibility issues in third-party Python code that (incorrectly) relies on dict ordering being relatively stable and/or in insertion order, etc. etc.

(The only reason I mention 3.6 is because the insertion-order behaviour there simply makes it easier to have a 'reverse' order)