With the [markerClusterGroup](https://github.com/Leaflet/Leaflet.markercluster) leaflet plugin, calling the [spiderfy](https://github.com/Leaflet/Leaflet.markercluster) function twice automatically closes the opened popup.

This seems to be due to [this piece of code](https://github.com/Leaflet/Leaflet.markercluster/blob/499f71caa1fe8a4efcf91b85e42553f9a90306f1/src/MarkerCluster.Spiderfier.js#L313) in the `unspiderfy` function, that is called automatically by the second `spiderfy` call.

    var tiles = L.tileLayer(...);
    var map = L.map(...);
    var coords = Array(...);
    var mcg = L.markerClusterGroup();
    var markers = Array();
    
    for (var i = 0; i < 100; i++) {
      var c = coords[i];
      var marker = L.marker(new L.LatLng(a[0], a[1]));
      markers.push(marker)
      marker.bindPopup("Point " + i);
      mcg.addLayer(marker);
    }

    function openPoint(i) {
        var marker = markers[i];
      	 var cluster = mcg.getVisibleParent(marker);
        if(cluster && cluster.spiderfy) {
        	cluster.spiderfy();
        }
    }

    map.addLayer(mcg);

    var x = ...;
    var y = ...;
    openPoint(x)            // Spiderfies the point x
    markers[x].openPopup(); // Opens the popup for the point x
    openPoint(y)            // Spiderfies the point y, and sadly closes the previous popup

[Here is a fiddle](https://jsfiddle.net/azmeuk/x7e8vc5p/2/) that illustrates the behavior I describe. Just click on buttons to spiderfy groups of items. Open a popup. And then click on another button to spiderfy another group of items. And see that the popup is closing.


How can I prevent this behavior?