Fix bug, in multiurlpicker where you cannot deselect a selected entity.

(cherry picked from commit 3385947c4e)

src/Umbraco.Web.UI.Client/src/views/common/infiniteeditors/linkpicker/linkpicker.controller.js

@@ -128,6 +128,13 @@ angular.module("umbraco").controller("Umbraco.Editors.LinkPickerController",
             eventsService.emit("dialogs.linkPicker.select", args);
 
             if ($scope.currentNode) {
+                if ($scope.currentNode.id == args.node.id && $scope.currentNode.selected) {
+                    $scope.model.target = {};
+                    $scope.currentNode.selected = false;
+
+                    return;
+                }
+
                 //un-select if there's a current one selected
                 $scope.currentNode.selected = false;
             }