When doing a custom build using a different AMD module name like

grunt custom --amd=""

or

grunt custom --amd="customname"

the

define('exports/amd',[
	"../core"
], function( jQuery ) {

won't be removed.

This means that when used with RequireJS

define(['customname'], function (jQuery) {
    // ...
});

doesn't return the jQuery object because it defines always the name "exports/amd" for the module.