Revert "Merge v1.4.2 into master"

vendor/github.com/NYTimes/gziphandler/gzip.go

@@ -150,9 +150,7 @@ func (w *GzipResponseWriter) startGzip() error {
 
 // WriteHeader just saves the response code until close or GZIP effective writes.
 func (w *GzipResponseWriter) WriteHeader(code int) {
-	if w.code == 0 {
-		w.code = code
-	}
+	w.code = code
 }
 
 // init graps a new gzip writer from the gzipWriterPool and writes the correct
@@ -192,16 +190,10 @@ func (w *GzipResponseWriter) Close() error {
 // http.ResponseWriter if it is an http.Flusher. This makes GzipResponseWriter
 // an http.Flusher.
 func (w *GzipResponseWriter) Flush() {
-	if w.gw == nil {
-		// Only flush once startGzip has been called.
-		//
-		// Flush is thus a no-op until the written body
-		// exceeds minSize.
-		return
+	if w.gw != nil {
+		w.gw.Flush()
 	}
 
-	w.gw.Flush()
-
 	if fw, ok := w.ResponseWriter.(http.Flusher); ok {
 		fw.Flush()
 	}