Original cache objects should not be immutable [#2860 state:resolved]

Signed-off-by: Yehuda Katz + Carl Lerche <ykatz+clerche@engineyard.com>

activesupport/lib/active_support/cache/memory_store.rb

@@ -26,7 +26,7 @@ module ActiveSupport
 
       def write(name, value, options = nil)
         super
-        @data[name] = value.freeze
+        @data[name] = (value.duplicable? ? value.dup : value).freeze
       end
 
       def delete(name, options = nil)

activesupport/test/caching_test.rb

@@ -176,6 +176,12 @@ class MemoryStoreTest < ActiveSupport::TestCase
     assert_raise(ActiveSupport::FrozenObjectError) { @cache.read('foo').gsub!(/.*/, 'baz') }
     assert_equal 'bar', @cache.read('foo')
   end
+
+  def test_original_store_objects_should_not_be_immutable
+    bar = 'bar'
+    @cache.write('foo', bar)
+    assert_nothing_raised { bar.gsub!(/.*/, 'baz') }
+  end
 end
 
 uses_memcached 'memcached backed store' do