This is almost a straight revert of the various GTFO -> GOAWAY changes. It seems like this is the popular move as per the discussion on the httpbis mailing list.

Arguments for the revert:

GOAWAY is self-descriptive and serves it purpose well. Editorial changes that don't clearly improve the spec should be discouraged so we can reach a stable spec sooner (granted this change doesn't affect the wire at all, but documentation churn counts too). GTFO is crass and doesn't belong in internet standards. GTFO,...