Fixed merging with self bug.

Src/Newtonsoft.Json.Tests/Linq/MergeTests.cs

@@ -46,6 +46,14 @@ namespace Newtonsoft.Json.Tests.Linq
     [TestFixture]
     public class MergeTests : TestFixtureBase
     {
+        [Test]
+        public void MergeSelf()
+        {
+            var a = new JArray { "1", "2" };
+            a.Merge(a, new JsonMergeSettings { MergeArrayHandling = MergeArrayHandling.Replace });
+            Assert.AreEqual(a, new JArray { "1", "2" });
+        }
+
         [Test]
         public void MergeNullString()
         {

Src/Newtonsoft.Json/Linq/JContainer.cs

@@ -1164,6 +1164,8 @@ namespace Newtonsoft.Json.Linq
 #endif
                     break;
                 case MergeArrayHandling.Replace:
+                    if (target == content)
+                        break;
                     target.ClearItems();
                     foreach (JToken item in content)
                     {