Update build

dist/leaflet.markercluster-src.js

@@ -273,6 +273,10 @@ L.MarkerClusterGroup = L.FeatureGroup.extend({
 
 	//Returns true if the given layer is in this MarkerClusterGroup
 	hasLayer: function (layer) {
+		if (layer._noHas) {
+			return false;
+		}
+
 		if (this._needsClustering.length > 0) {
 			var anArray = this._needsClustering;
 			for (var i = anArray.length - 1; i >= 0; i--) {
@@ -1032,7 +1036,9 @@ L.MarkerCluster = L.Marker.extend({
 			this._backupLatlng = this._latlng;
 			this.setLatLng(startPos);
 		}
+		this._noHas = true;
 		L.FeatureGroup.prototype.addLayer.call(this._group, this);
+		delete this._noHas;
 	},
 
 	_recursivelyAnimateChildrenIn: function (bounds, center, maxZoom) {
@@ -1111,7 +1117,9 @@ L.MarkerCluster = L.Marker.extend({
 						nm.setOpacity(0);
 					}
 
+					nm._noHas = true;
 					L.FeatureGroup.prototype.addLayer.call(c._group, nm);
+					delete nm._noHas;
 				}
 			},
 			function (c) {
@@ -1168,7 +1176,9 @@ L.MarkerCluster = L.Marker.extend({
 				for (i = c._childClusters.length - 1; i >= 0; i--) {
 					m = c._childClusters[i];
 					if (!exceptBounds || !exceptBounds.contains(m._latlng)) {
-						L.FeatureGroup.prototype.removeLayer.call(c._group, m);
+						if (L.FeatureGroup.prototype.hasLayer.call(c._group, m)) {
+							L.FeatureGroup.prototype.removeLayer.call(c._group, m);
+						}
 						m.setOpacity(1);
 					}
 				}
@@ -1641,7 +1651,9 @@ L.MarkerCluster.include(!L.DomUtil.TRANSITION ? {
 			m.setZIndexOffset(1000000); //Make these appear on top of EVERYTHING
 			m.setOpacity(0);
 
+			m._noHas = true;
 			L.FeatureGroup.prototype.addLayer.call(group, m);
+			delete m._noHas;
 
 			m._setPos(thisLayerPos);
 		}