> Just curious, can you elaborate why the ability to push gives you a tight
> feedback loop?

Notice how belabored the email-patch mechanism is for prospective
contributors without push access.  Nature of the beast I'm afraid... there's
always at least one niggling fixup for the smallest patch submission, and for a
50-commit-behind-50-commit-ahead merge, there's going to be order of 10
fixups.  The verbal back-and-forth required is prohibitively costly for a
largely inactive repo like emacs-chess.

The web-based "pull request" mechanism is much more sane than iterating emails
as it's always clear which of the author's iterations is latest, but that's a
separate issue.