improve docker entry script to avoid custom_config.json rebuild

docker-entrypoint.sh

@@ -5,10 +5,13 @@ if [ -d "/var/www/machete/themes/${theme}/" ]; then
 
     ## 复制对应皮肤的配置文件
     cd /var/www/machete/runtime/
-    rm -f custom_config.json
+
+    ## 避免容器重启后重新生成配置文件
+    if [ ! -f custom_config.json ]; then
         cp "../conf/custom_config_${theme}.json" ./custom_config.json
         chmod 777 custom_config.json
     fi
+fi
 
 ## 启动samba
 if [ -e /usr/sbin/smbd ]; then