fix: trailing_index function should ru first

Author: curbengh

lib/models/post.js

@@ -54,8 +54,8 @@ module.exports = ctx => {
   Post.virtual('permalink').get(function() {
     const { config } = ctx;
     let partial_url = url_for.call(ctx, this.path);
-    if (config.relative_link) partial_url = `/${partial_url}`;
     if (config.pretty_urls.trailing_index === false) partial_url = partial_url.replace(/index\.html$/, '');
+    if (config.relative_link) partial_url = `/${partial_url}`;
     return full_url_for.call(ctx, partial_url.replace(config.root, '/'));
   });