knockout.js 'ko' dissapears from page in event handler on Android Browser 4.0.4

I am observing very peculiar behaviour, when testing system on Samsung tablet some of links stopped working. To make it easier to debug I am using Chrome Developer tools emulator, when page is loaded I can call kncoukout.js global ko from console for debugging (like getting context for bound elements...) thing is when I am trying to debug from event handler ko vanishes.
Have a look at screenshot below.

I have been able to access ko when not in callback,
then I placed breakpoint in event handler and tried to access ko again on a click and it's not there anymore, and then it fails with error of ko not being there.
What is going on, how can ko just disappear?

Not that I think it matters (same happens in any event handler), but someone will ask for code that makes ko disappear.

 var parseHrefBinding = function (link) {
        var newHref = null;
        var boundEl = $(link).closest('[data-bind]')[0];
        if (boundEl) {
            var data = ko.dataFor(boundEl);
            if (data) {
                var a = document.createElement('a');
                a.setAttribute('data-bind', link.attributes['data-bind'].value);
                ko.applyBindings(data, a);
                newHref = a.href;
            }
        }

        return newHref;
    };

    $(document).on("click", "a", function () {
        var res = true;
        var link = this;
        var parent = $(link).parents('a')[0];
        if (parent) {
            // The default Android browser (V2-4.1) sets nested a[href] to their parent's href.
            var href = parent.href === link.href ? parseHrefBinding(link) : link.href;
            setTimeout(function () {
                document.location.href = href;
            }, 10);
            res = false;
        }

        return res;
    });

God this is epic, it turns out that to use globals in event handlers on Android Browser 4 one has to add window in front of ko eg. window.ko see screenshot below.

so fix was as simple as changing

var data = ko.dataFor(boundEl);
to
var data = window.ko.dataFor(boundEl);