I like the idea of experimentally trying the push workflow but, if we are all doing our jobs right, there should be very few changes going in after rc1 so most committers won't need to push anything to the 3.5.0rc repo and, if for some reason they aren't able to use Bitbucket, someone could do it for them.
https://hg.python.org/release/file/b7529318e7cc/3.4/threefourtool.pyI have since given up this foolish desire. I'll be happy to have a nice grubby revision DAG if it means I can spend more time on the internet cruising for funny cat videos.