Do not change original data by kv.group

Src/api.js

@@ -174,11 +174,7 @@
 				});
 			};
 
-			obj.errors = result;
-			obj.isValid = function () {
-				return obj.errors().length === 0;
-			};
-			obj.isAnyMessageShown = function () {
+			result.isAnyMessageShown = function () {
 				var invalidAndModifiedPresent = false;
 
 				// ensure we have latest changes

Src/ko.extensions.js

@@ -36,7 +36,7 @@ ko.validatedObservable = function (initialValue, options) {
 
 	var obsv = ko.observable(initialValue);
 	obsv.errors = ko.validation.group(initialValue, options);
-	obsv.isValid = ko.observable(initialValue.isValid());
+	obsv.isValid = ko.observable(obsv.errors().length === 0);
 
 
 	if (ko.isObservable(obsv.errors)) {

Tests/api-tests.js

@@ -274,7 +274,7 @@ test('validatedObservable does not show error message when not modified', functi
 	});
 
 	ok(obj(), 'observable works');
-	ok(!obj().isAnyMessageShown(), 'validation error message is hidden');
+	ok(!obj.errors.isAnyMessageShown(), 'validation error message is hidden');
 
 });
 
@@ -288,7 +288,7 @@ test('validatedObservable does not show error message when modified but correct'
 	obj().testObj2('a');
 
 	ok(obj(), 'observable works');
-	ok(!obj().isAnyMessageShown(), 'validation error message is hidden');
+	ok(!obj.errors.isAnyMessageShown(), 'validation error message is hidden');
 
 });
 
@@ -301,7 +301,7 @@ test('validatedObservable show error message when at least one invalid and modif
 	obj().testObj.isModified(true);
 
 	ok(obj(), 'observable works');
-	ok(obj().isAnyMessageShown(), 'validation error message is shown');
+	ok(obj.errors.isAnyMessageShown(), 'validation error message is shown');
 
 });