improve machete docker image download

install.sh

@@ -284,8 +284,11 @@ echo ""
 detectDockerImageExists "filesite/machete"
 imgExist=$?
 if [ $imgExist -eq 0 ]; then
+    if [ ! -f ./machete.tar ]; then
         echo "下载machete的docker镜像，文件大小89M，预计需要 5 - 10 分钟..."
         curl -o machte.tar "https://static.jialuoma.cn/docker_images/machete.tar"
+    fi
+
     if [ -f ./machete.tar ]; then
         sumok="eacbdfb33873e79d1eccca7fa2d0706a"
         checkRes=`md5 machete.tar | grep -v grep | grep "${sumok}" | wc -l`