fallback to not ranged request if server lacks HEAD

Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>

common/download.go

@@ -215,25 +215,31 @@ func (d *HTTPDownloader) Download(dst *os.File, src *url.URL) error {
 	}
 
 	resp, err := httpClient.Do(req)
+	if err != nil || resp.StatusCode != 200 {
+		req.Method = "GET"
+		resp, err = httpClient.Do(req)
 		if err != nil {
 			return err
 		}
+	}
 
-	req.Method = "GET"
 	if resp.StatusCode != 200 {
 		log.Printf(
 			"Non-200 status code: %d. Getting error body.", resp.StatusCode)
-
-		resp, err := httpClient.Do(req)
+		if req.Method != "GET" {
+			req.Method = "GET"
+			resp, err = httpClient.Do(req)
 			if err != nil {
 				return err
 			}
+		}
 		errorBody := new(bytes.Buffer)
 		io.Copy(errorBody, resp.Body)
 		return fmt.Errorf("HTTP error '%d'! Remote side responded:\n%s",
 			resp.StatusCode, errorBody.String())
 	}
 
+	req.Method = "GET"
 	d.progress = 0
 
 	if resp.Header.Get("Accept-Ranges") == "bytes" {