init: move to new style import This unify with the new core Mercurial usage and this will make future changes to the imports easier to track.

test: disable the new style rendering for "missing parent" The style kicks in when we display a partial tree. Supporting test running both 3.7 and default with this is painful, we disable the new feature for now.

tests: add pyflakes test

setup: make sure we use the imported module This prevent pyflakes to complains about it (and work around any possible demand import magic. I'm not sure why we do this important dance at all, but I'm leaving it there in doubt.