Highstock bug: dragging one navigator handle changes both dates - highcharts

Question

When dragging one of the navigator handles, both dates change.
To reproduce, go to http://jsfiddle.net/rNer2/5/ and drag one of the navigator handles. In the provided test case, the problem only occurs the first time a handle is dragged. It can actually also happen in other situations, but perhaps fixing it here will fix it for the other cases as well.
See duplicate code below:
<div id="container" style="height: 400px; min-width: 600px"></div>
<script src="http://code.highcharts.com/stock/highstock.js"></script>
<script src="http://code.highcharts.com/stock/modules/exporting.js"></script>
<div id="mindate" style="position:absolute;top:40px;left:0px;margin-left:20px;"></div>
<div id="maxdate" style="position:absolute;top:40px;right:0px;margin-right:50px;">
$(function() {
var data = [];
for (var i = 1971; i < 2020; ++i) {
data.push([Date.UTC(i, 0, 1), 1]);
}
var chart = new Highcharts.StockChart({
chart: {
renderTo: 'container',
type: 'column',
events: {
load: function() {
displayDates(this.xAxis[0].getExtremes());
}
}
},
xAxis: {
ordinal: false,
events: {
afterSetExtremes: function(e) {
displayDates(e);
}
},
min: Date.UTC(1984, 0, 1),
max: Date.UTC(1988, 0, 1)
},
series: [{
data: data
}]
});
});
function displayDates(e) {
$('#mindate').html(Highcharts.dateFormat('%m/%d/%y %I:%M:%S%p', e.min));
$('#maxdate').html(Highcharts.dateFormat('%m/%d/%y %I:%M:%S%p', e.max));
}

Answer 1

Please familiar with very simple example:
http://jsfiddle.net/ebLTE/
$('#container').highcharts('StockChart', {
chart:{
type:'column'
},
rangeSelector : {
selected : 1
},
title : {
text : 'AAPL Stock Price'
},
xAxis:{
min:1172707200000,
max:1175126400000
},
series : [{
name : 'AAPL',
data : data,
tooltip: {
valueDecimals: 2
}
}]
});