D3 Pie chart not updating correctly - d3.js

Question

I got the following D3 v4 pie chart, every time I try updating it the data doesn't update correctly. I have been reading around tried following some other example, but just can't seem to get it to work. Current update function looks like this:
function PieGenUpdater(data, colourRangeIn) {
var dataset = data;
var width = 400;
var height = 400;
var radius = Math.min(width, height) / 2;
var arc = d3.arc()
.innerRadius(radius/1.5)
.outerRadius(radius);
var pie = d3.pie()
.value(function(d) { return d.percent; })
.sort(null);
var svg = d3.select('#c-pie');
var path = svg.selectAll('path').data(pie(dataset));
path.enter()
.append("path")
.attr('fill', function(d, i) {
return d.data.color;
})
.attr("d", arc)
.each(function(d) {this._current = d;} );
path.transition()
.attrTween("d", arcTweenCoverage);
path.exit().remove();
// Store the displayed angles in _current.
// Then, interpolate from _current to the new angles.
// During the transition, _current is updated in-place by d3.interpolate.
function arcTweenCoverage(a) {
var i = d3.interpolate(this._current, a);
this._current = i(0);
return function(t) {
return arc(i(t));
};
}
}
https://jsfiddle.net/mahsan/zup6kafk/
Any help is greatly appreciated.

Answer 1

Here is the 4 years too late answer...
In PieGenUpdater change
var path = svg.selectAll('path').data(pie(dataset));
to
var path = svg.select('g').selectAll('path').data(pie(dataset));
In your update function you were adding the additional paths from dataset 1 directly under element instead of the element