fixes #1450

Additionally:
* Adds basic negated id metatag.
* Post set presenter now uses the post set's tag string, not the
parameter from the URL.

app/controllers/posts_controller.rb

@@ -22,8 +22,8 @@ class PostsController < ApplicationController
     @post = Post.find(params[:id])
     @post_flag = PostFlag.new(:post_id => @post.id)
     @post_appeal = PostAppeal.new(:post_id => @post.id)
-    @parent_post_set = PostSets::Post.new("parent:#{@post.id}")
-    @child_post_set = PostSets::Post.new("parent:#{@post.parent_id}")
+    @parent_post_set = PostSets::Post.new("parent:#{@post.id} -id:#{@post.id}")
+    @child_post_set = PostSets::Post.new("id:#{@post.parent_id} status:any")
     respond_with(@post)
   end