Mapping not saved when data is an array

[jt000]

The problem is that when using ko.mapping for a single object the mapping is retained for later use:

    var mapping = {
        id: { create: function(o) { return 'ID#'+o; } },
    };

    var datum = {id: 500};
    var datumVm = ko.mapping.fromJS(datum, mapping);
    // ko.mapping.isMapped(datumVm) is defined

However, when using ko.mapping to map an array, the mapping isn't saved which prevents hiding of added values:

    var mapping = {
        id: { create: function(o) { return 'ID#'+o; } },
    };

    var data = [{id: 500}, {id:499}];
    var dataVm = ko.mapping.fromJS(data, mapping);
    // ko.mapping.isMapped(dataVm) is NOT defined

Here is a fiddle demonstrating the issue: http://jsfiddle.net/vkd3nefa/1/

[jt000]

Note that if I setting __ko_mapping__ on each element in the VM's array, then this does work properly:
see http://jsfiddle.net/vkd3nefa/2/ for example