From 40c7f74543c36670db5302df6450f4e224b685ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mehmet=20Emin=20=C4=B0NA=C3=87?= <mehmetemininac@gmail.com>
Date: Mon, 4 May 2015 18:54:14 +0300
Subject: [PATCH] deep_dup method, remove old key from duplicated hash to avoid
 unnecessary pairs

---
 .../lib/active_support/core_ext/object/deep_dup.rb          | 1 +
 activesupport/test/core_ext/object/deep_dup_test.rb         | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/activesupport/lib/active_support/core_ext/object/deep_dup.rb b/activesupport/lib/active_support/core_ext/object/deep_dup.rb
index 0191d2e9733c..ad5b2af161d5 100644
--- a/activesupport/lib/active_support/core_ext/object/deep_dup.rb
+++ b/activesupport/lib/active_support/core_ext/object/deep_dup.rb
@@ -40,6 +40,7 @@ class Hash
   #   dup[:a][:c]  # => "c"
   def deep_dup
     each_with_object(dup) do |(key, value), hash|
+      hash.delete(key)
       hash[key.deep_dup] = value.deep_dup
     end
   end
diff --git a/activesupport/test/core_ext/object/deep_dup_test.rb b/activesupport/test/core_ext/object/deep_dup_test.rb
index 91d558dbb521..38fbe1f83673 100644
--- a/activesupport/test/core_ext/object/deep_dup_test.rb
+++ b/activesupport/test/core_ext/object/deep_dup_test.rb
@@ -50,4 +50,10 @@ def test_object_deep_dup
     assert dup.instance_variable_defined?(:@a)
   end
 
+  def test_deep_dup_with_hash_class_key
+    hash = { Fixnum => 1 }
+    dup = hash.deep_dup
+    assert_equal dup.keys.length, 1
+  end
+
 end