Whitelist the alternative raw url

app/assets/javascripts/discourse/lib/url.js.es6

@@ -8,6 +8,7 @@ const TOPIC_REGEXP = /\/t\/([^\/]+)\/(\d+)\/?(\d+)?/;
 // We can add links here that have server side responses but not client side.
 const SERVER_SIDE_ONLY = [
   /^\/posts\/\d+\/raw/,
+  /^\/raw\/\d+/,
   /\.rss$/,
   /\.json/,
 ];