reused := !atomic.CompareAndSwapUint32(&cc.reused, 0, 1)
		http2traceGotConn(req, cc, reused)
		res, err := cc.RoundTrip(req)
		if err != nil && retry <= 6 {
			roundTripErr := err
			if req, err = http2shouldRetryRequest(req, err); err == nil {
				// After the first retry, do exponential backoff with 10% jitter.
				if retry == 0 {
					t.vlogf("RoundTrip retrying after failure: %v", roundTripErr)
					continue
				}