backout: backed out changeset 5d83a40cd3f8 This is the re-send of the backout in D11757 that I accidentally queued. I'll rewrite the original commit message: ...sigh We do not have Python 3 packaging for thg on Windows where the vast majority of of users use the thg installer for Mercurial. Until this is done (hopefully this cycle), we're keeping Python. (end of the old commit message) On top of this, we have a solid lead to have competent people take care of this packaging issue for us in time for the 6.1 release, which is really the main reason for us to wait. We're trying our best to make this work, so please bear with us. Differential Revision: https://phab.mercurial-scm.org/D11770