fix Reveal Spoiler Thumbnails on archived posts

src/General/Get.coffee

@@ -217,6 +217,7 @@ Get =
     thread = g.threads["#{boardID}.#{threadID}"] or
       new Thread threadID, board
     post = new Post Build.post(o), thread, board, {isArchived: true}
+    post.file.thumbURL = o.file.turl
     post.isFetchedQuote = true
     Main.callbackNodes Post, [post]
     Get.insert post, root, context

src/General/lib/post.class

@@ -149,10 +149,7 @@ class Post
     unit  = ['B', 'KB', 'MB', 'GB'].indexOf @file.size.match(/\w+$/)[0]
     size *= 1024 while unit-- > 0
     @file.sizeInBytes = size
-    @file.thumbURL = if that.isArchived
-      thumb.src
-    else
-      "#{location.protocol}//t.4cdn.org/#{@board}/#{@file.URL.match(/(\d+)\./)[1]}s.jpg"
+    @file.thumbURL = "#{location.protocol}//t.4cdn.org/#{@board}/#{@file.URL.match(/(\d+)\./)[1]}s.jpg"
     @file.isImage = /(jpg|png|gif)$/i.test @file.URL
     @file.isVideo = /webm$/i.test @file.URL
     nameNode = $ 'a', fileText