bug of unbinding swipeleft/swiperight handler

[egana]

When I bind both 'swipeleft' and 'swiperight' handler to the same element and then unbind the 'swiperight' handler, 'swipeleft' event handler is no longer fired.

Test:
http://jsbin.com/acIRUBo/66/edit
In the above test page, first 'swipeleft' and 'swiperight' handler is bound to #target element.
By the clicking the button, 'swiperight' handler is unbound. Since 'swipeleft' handler is not unbound, you expect that 'swipeleft' handler is still fired, but actually it's not fired anymore.

In fact, at the following line, when teardown 'swiperight' event handler, all the 'swipe' handler is unbound.
https://github.com/jquery/jquery-mobile/blob/18f872d0174e418c0ac1433267a1e9ea13a4263a/js/events/touch.js#L325