Mark Class as not being duplicable. [#829 state:resolved]

Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

activesupport/lib/active_support/core_ext/duplicable.rb

@@ -35,3 +35,9 @@ def duplicable?
     false
   end
 end
+
+class Class #:nodoc:
+  def duplicable?
+    false
+  end
+end

activesupport/test/core_ext/duplicable_test.rb

 require 'abstract_unit'
 
 class DuplicableTest < Test::Unit::TestCase
-  NO  = [nil, false, true, :symbol, 1, 2.3, BigDecimal.new('4.56')]
+  NO  = [nil, false, true, :symbol, 1, 2.3, BigDecimal.new('4.56'), Class.new]
   YES = ['1', Object.new, /foo/, [], {}, Time.now]
 
   def test_duplicable