Merge pull request #1579 from bradleybuda/master

Date#freeze fails when called more than once in 1.8

activesupport/lib/active_support/core_ext/date/freeze.rb

@@ -5,7 +5,7 @@
 # first call will result in a frozen object error since the memo
 # instance variable is uninitialized.
 #
-# Work around by eagerly memoizing before freezing.
+# Work around by eagerly memoizing before the first freeze.
 #
 # Ruby 1.9 uses a preinitialized instance variable so it's unaffected.
 # This hack is as close as we can get to feature detection:
@@ -17,11 +17,13 @@ if RUBY_VERSION < '1.9'
     if frozen_object_error.message =~ /frozen/
       class Date #:nodoc:
         def freeze
+          unless frozen?
             self.class.private_instance_methods(false).each do |m|
               if m.to_s =~ /\A__\d+__\Z/
                 instance_variable_set(:"@#{m}", [send(m)])
               end
             end
+          end
 
           super
         end

activesupport/test/core_ext/date_ext_test.rb

@@ -454,4 +454,10 @@ class DateExtBehaviorTest < Test::Unit::TestCase
       Date.today.freeze.inspect
     end
   end
+
+  def test_can_freeze_twice
+    assert_nothing_raised do
+      Date.today.freeze.freeze
+    end
+  end
 end