master: changing 301 to 308 on redirect to volume servers

fix https://github.com/chrislusf/seaweedfs/issues/1454

weed/server/master_server_handlers_admin.go

@@ -110,7 +110,7 @@ func (ms *MasterServer) redirectHandler(w http.ResponseWriter, r *http.Request)
 		} else {
 			url = util.NormalizeUrl(loc.PublicUrl) + r.URL.Path
 		}
-		http.Redirect(w, r, url, http.StatusMovedPermanently)
+		http.Redirect(w, r, url, http.StatusPermanentRedirect)
 	} else {
 		writeJsonError(w, r, http.StatusNotFound, fmt.Errorf("volume id %s not found: %s", vid, location.Error))
 	}