Handle orphaned gestures.

[mbostock]

The equivalent of d3/d3-brush#18, but for d3-zoom. If the browser fails to deliver a mouseup (or touchend or touchcancel) event, the active gesture can get orphaned, in which case no new gestures can start or end.

[MarkusMannheim]

May I get an update on this? This affects all of my scripts that use d3.zoom() when accessed via mobiles/touchscreens. When the user pinches to zoom in/zoom out, and then tries to pan by dragging with a single touch, the program behaves as though two fingers are still touching the screen - i.e. it doesn't fire a touchend/touchcancel event, or enough touchend/touchcancel events.

The bug occurs in iOS and Android, across all browsers I tried (though I wasn't exhaustive).

Is there a workaround?