RSpec rcov task does not work

foo.rb

module Foo
  def self.number
    8
  end
end

foo_spec.rb

require 'rspec'

require File.expand_path('../foo', __FILE__)

describe Foo do
  describe '.number' do
    it 'is 9' do
      Foo.number.should == 9
    end
  end
end

Gemfile

source :rubygems

gem 'rake'
gem 'rspec', '2.12.0'
gem 'rcov'

output.txt

$ bundle show
Gems included by the bundle:
  * bundler (1.1.rc)
  * diff-lcs (1.1.3)
  * rake (0.9.2)
  * rcov (0.9.11)
  * rspec (2.7.0)
  * rspec-core (2.7.0)
  * rspec-expectations (2.7.0)
  * rspec-mocks (2.7.0)
$ bundle exec rake spec
/Users/rsutphin/.rvm/rubies/ruby-1.8.7-p352/bin/ruby -S rspec foo_spec.rb
F

Failures:

  1) Foo.number is 9
     Failure/Error: Foo.number.should == 9
       expected: 9
            got: 8 (using ==)
     # ./foo_spec.rb:8

Finished in 0.07978 seconds
1 example, 1 failure

Failed examples:

rspec ./foo_spec.rb:7 # Foo.number is 9
rake aborted!
ruby /Users/rsutphin/.rvm/rubies/ruby-1.8.7-p352/bin/ruby -S rspec foo_spec.rb failed

Tasks: TOP => spec
(See full trace by running task with --trace)
$ bundle exec rake spec:rcov
/Users/rsutphin/.rvm/rubies/ruby-1.8.7-p352/bin/ruby -S rcov -Ispec:lib foo_spec.rb

Rakefile

require 'rspec/core/rake_task'

desc "Run all specs"
RSpec::Core::RakeTask.new('spec') do |t|
  t.pattern = 'foo_spec.rb'
  t.verbose = true
end

desc "Run all specs with rcov"
RSpec::Core::RakeTask.new('spec:rcov') do |t|
  t.pattern = 'foo_spec.rb'
  t.verbose = true
  t.rcov = true
end