Combination of edge cases triggers ~200ms delay in TTFB

[pmeenan]

Very cool. I expect that will actually happen a lot in the wild under all sorts of different conditions so it's probably quite a win for nginx perf. In your tests it was pretty clear because it was showing in TTFB but from the looks of the patch it might commonly just show as an extra 200ms delivering the last bit of data which might be less obvious but still pretty nasty.