Rails 3.0.3 has many#create does not create a record

Given a these models

class OrganizingCity < ActiveRecord::Base
  has_many :tables
end
class Table < ActiveRecord::Base
  belongs_to :organizing_city
end

and the specs (using FixtureReplacement)

describe OrganizingCity do
  describe "create a table" do
    it "through tables#create add a table to the has_many association" do
      organizing_city = create_organizing_city
      organizing_city.tables.create new_table.attributes
      organizing_city.reload
      organizing_city.tables.size.should == 1
    end
    it "through creating a new table adds a table to the has many association" do
      organizing_city = create_organizing_city
      Table.create organizing_city.tables.create new_table(:organizing_city => organizing_city).attributes
      organizing_city.reload
      organizing_city.tables.size.should == 1
    end
  end
end

then the first one fails and the second one passes.