Issue with elasticsearch node client.close

gistfile1.js

'use strict';

var elasticsearch = require('elasticsearch');
var deferred = require('deferred');

function Foo () {
    this.client = new elasticsearch.Client({
            hosts : 'localhost:9200',
            log: 'error'
    });
}

Foo.prototype.close = function() {
    this.client.close();
}

Foo.prototype.createIndex = function (indexName) {
    var d = deferred();

    this.client.indices.create({
        index: indexName,
        body: {
            "mappings" : {
                "myType" : {
                    "_id" : {
                        "path" : "id"
                    }
                }
            }
        }
    }).done(function(body) {
        d.resolve(body);
    }, function(error) {
        d.reject(new Error('Unable to create user index. Error: ' + JSON.stringify(error)));
    });

    return d.promise;
}

Foo.prototype.deleteIndex = function (indexName) {
    var d = deferred();

    this.client.indices.delete({index:indexName}).done(function(body) {
        d.resolve(body);
    }, function(error) {
        d.reject(new Error('Unable to delete user index. Error: ' + JSON.stringify(error)));
    });

    return d.promise;
}

Foo.prototype.doesIndexExist = function (indexName) {
    var d = deferred();

    this.client.indices.exists({index:indexName}).done(function(body) {
        d.resolve(body);
    }, function(error) {
        d.reject(new Error('Unable to check existence of user index. Error: ' + JSON.stringify(error)));
    });

    return d.promise;
}

Foo.prototype.resetIndex = function (indexName) {
    var d = deferred();

    var _this = this;

    this.doesIndexExist(indexName).then(function(exists) {
        if(exists) {
            _this.deleteIndex(indexName).then(function(body) {
                return _this.createIndex(indexName);
            }).done(function(body) { 
                d.resolve(true); 
            }, function(error) {
                d.reject(error);
            });
        } else {
            _this.createIndex(indexName).then(function(body) { 
                d.resolve(true); 
            }, function(error) {
                d.reject(error);
            });
        }
    }, function (error) {
        d.reject(error);
    });

    return d.promise;
}

var a = new Foo();

// doesn't terminate if indices already exist
a.resetIndex("test").then(function(b) {
   return a.resetIndex("test1");
}, function(e) {
    console.error(e);
}).done(function(b) {
    console.log(b);
    a.close();
}, function(e) {
    console.error(e);
});