if wr.stream.wroteHeaders {
			// We do not need to notify wr.done because this frame is
			// never written with wr.done != nil.
			if wr.done != nil {
				panic("wr.done != nil for write100ContinueHeadersFrame")
			}
			ignoreWrite = true
		}
	}

	if !ignoreWrite {
		if wr.isControl() {
			sc.queuedControlFrames++
			// For extra safety, detect wraparounds, which should not happen,