Fixed zero length multibulk. Passing null not an empty array

index.js

@@ -118,7 +118,7 @@ RedisReplyParser.prototype.execute = function (incoming_buf) {
                 this.multi_bulk_replies = [];
                 this.state = "type";
                 if (0 == this.multi_bulk_length) {
-                    this.send_reply([]);
+                    this.send_reply(null);
                 }
             } else {
                 this.emit("error", new Error("didn't see LF after NL reading multi bulk count"));

test.js

@@ -218,7 +218,7 @@ tests.MULTIBULK_ZERO_LENGTH = function () {
     var name = "MULTIBULK_ZERO_LENGTH";
     client.KEYS(['users:*'], function(err, results){
         assert.strictEqual(null, err, 'error on empty multibulk reply');
-        assert.strictEqual(0, results.length);
+        assert.strictEqual(null, results);
         next(name);
     });
 };