.arcconfig

node: make bin() be a wrapper instead of just an alias

This includes a full backout of 59affe7e and 30d0cb27. Per the review
of the former, we'd rather adapt the API to behave like it used to (at
least for now), and take a second run at it if it shows up in our
performance numbers. I ran perfrevlogindex with and without this
change and it didn't make a measurable difference, so maybe it's fine
(despite my intuition to the contrary).

Differential Revision: https://phab.mercurial-scm.org/D2279

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