fixes #1688

app/models/post.rb

@@ -30,7 +30,6 @@ class Post < ActiveRecord::Base
   has_many :children, :class_name => "Post", :foreign_key => "parent_id", :order => "posts.id"
   has_many :disapprovals, :class_name => "PostDisapproval", :dependent => :destroy
   validates_uniqueness_of :md5
-  validates_presence_of :parent, :if => lambda {|rec| !rec.parent_id.nil?}
   validate :post_is_not_its_own_parent
   attr_accessible :source, :rating, :tag_string, :old_tag_string, :last_noted_at, :parent_id, :as => [:member, :builder, :gold, :platinum, :contributor, :janitor, :moderator, :admin, :default]
   attr_accessible :is_rating_locked, :is_note_locked, :as => [:builder, :contributor, :janitor, :moderator, :admin]