Have Deferred.always return the object onto which it is currently att…

…ached to enable true chainability. Fixes #10723. Unit tests added.

src/deferred.js

@@ -33,7 +33,8 @@ jQuery.extend({
 					return this;
 				},
 				always: function() {
-					return deferred.done.apply( deferred, arguments ).fail.apply( deferred, arguments );
+					deferred.done.apply( deferred, arguments ).fail.apply( deferred, arguments );
+					return this;
 				},
 				pipe: function( fnDone, fnFail, fnProgress ) {
 					return jQuery.Deferred(function( newDefer ) {

test/unit/deferred.js

@@ -56,6 +56,19 @@ jQuery.each( [ "", " - new operator" ], function( _, withNew ) {
 	});
 } );
 
+test( "jQuery.Deferred - chainability", function() {
+
+	var methods = "resolve reject notify resolveWith rejectWith notifyWith done fail progress then always".split( " " ),
+		defer = jQuery.Deferred();
+
+	expect( methods.length );
+
+	jQuery.each( methods, function( _, method ) {
+		var object = { m: defer[ method ] };
+		strictEqual( object.m(), object, method + " is chainable" );
+	});
+});
+
 test( "jQuery.Deferred.pipe - filtering (done)", function() {
 
 	expect(4);