use :dependent => :destroy rather than :dependent => true

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5160 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/test/fixtures/topic.rb

 class Topic < ActiveRecord::Base
-  has_many :replies, :include => [:user], :dependent => true
-end
\ No newline at end of file
+  has_many :replies, :include => [:user], :dependent => :destroy
+end