Fix sitemap.xml: Exclude redirected links

Author: Smoke-ck

sitemap.xml

@@ -4,9 +4,11 @@ layout: null
 
 <?xml version="1.0" encoding="UTF-8"?>
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+  {% assign redirect_links = site.pages | concat: site.posts | map: 'redirect_from' | compact | flatten %}
+
   {% for page in site.pages %}
     {% if page.url contains '.html' or page.url contains '/' %}
-      {% unless page.sitemap_exclude or page.url contains '404.html' or page.url contains '.xml' or page.url contains '.css'%}
+      {% unless redirect_links contains page.url or page.sitemap_exclude or page.url contains '404.html' or page.url contains '.xml' or page.url contains '.css'%}
         <url>
           <loc>{{ site.url }}{{ page.url | remove: 'index.html' | remove: '.html' }}</loc>
           <lastmod>{{ page.date-modified | default: site.default-date-modified | date: '%Y-%m-%d' }}</lastmod>