Refactor Post#related_posts to build the index in a different method

lib/jekyll/post.rb

@@ -229,6 +229,16 @@ module Jekyll
       return [] unless posts.size > 1
 
       if self.site.lsi
+        build_index
+
+        related = self.class.lsi.find_related(self.content, 11)
+        related - [self]
+      else
+        (posts - [self])[0..9]
+      end
+    end
+
+    def build_index
       self.class.lsi ||= begin
         puts "Starting the classifier..."
         lsi = Classifier::LSI.new(:auto_rebuild => false)
@@ -239,12 +249,6 @@ module Jekyll
         puts ""
         lsi
       end
-
-        related = self.class.lsi.find_related(self.content, 11)
-        related - [self]
-      else
-        (posts - [self])[0..9]
-      end
     end
 
     # Add any necessary layouts to this post.