Revert "Fix issue on status code when writer was flushed"

This reverts commit 0f67f3f.

gzip.go

@@ -82,7 +82,6 @@ type GzipResponseWriter struct {
 	buf     []byte // Holds the first part of the write before reaching the minSize or the end of the write.
 
 	contentTypes []string // Only compress if the response is one of these content-types. All are accepted if empty.
-	flushed      bool     // Indicate if the stream was already flushed
 }
 
 // Write appends data to the gzip writer.
@@ -170,8 +169,7 @@ func (w *GzipResponseWriter) init() {
 func (w *GzipResponseWriter) Close() error {
 	if w.gw == nil {
 		// Gzip not trigged yet, write out regular response.
-		// WriteHeader only if it wasn't already wrote by a Flush
-		if !w.flushed && w.code != 0 {
+		if w.code != 0 {
 			w.ResponseWriter.WriteHeader(w.code)
 		}
 		if w.buf != nil {
@@ -199,11 +197,7 @@ func (w *GzipResponseWriter) Flush() {
 	}
 
 	if fw, ok := w.ResponseWriter.(http.Flusher); ok {
-		if !w.flushed && w.code != 0 {
-			w.ResponseWriter.WriteHeader(w.code)
-		}
 		fw.Flush()
-		w.flushed = true
 	}
 }
 

gzip_test.go

@@ -306,23 +306,6 @@ func TestStatusCodes(t *testing.T) {
 	}
 }
 
-func TestStatusCodesFlushed(t *testing.T) {
-	handler := GzipHandler(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		rw.WriteHeader(http.StatusNotFound)
-		rw.(http.Flusher).Flush()
-		rw.Write([]byte("Not found"))
-	}))
-	r := httptest.NewRequest(http.MethodGet, "/", nil)
-	r.Header.Set(acceptEncoding, "gzip")
-	w := httptest.NewRecorder()
-	handler.ServeHTTP(w, r)
-
-	result := w.Result()
-	if result.StatusCode != http.StatusNotFound {
-		t.Errorf("StatusCode should have been 404 but was %d", result.StatusCode)
-	}
-}
-
 func TestIgnoreSubsequentWriteHeader(t *testing.T) {
 	handler := GzipHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(500)