Ensure _.xor returns an empty array when comparing the same array. [closes #2776]

lodash.js

@@ -4414,7 +4414,7 @@
 
         while (++othIndex < length) {
           var othArray = arrays[othIndex];
-          if (othArray !== array) {
+          if (othIndex != index) {
             result[index] = baseDifference(result[index] || array, othArray, iteratee, comparator);
           }
         }

test/test.js

@@ -25279,6 +25279,15 @@
       assert.deepEqual(actual, []);
     });
 
+    QUnit.test('`_.' + methodName + '` should return an empty array when comparing the same array', function(assert) {
+      assert.expect(1);
+
+      var array = [1],
+          actual = func(array, array, array);
+
+      assert.deepEqual(actual, []);
+    });
+
     QUnit.test('`_.' + methodName + '` should return an array of unique values', function(assert) {
       assert.expect(2);