Fixes transaction not getting cleaned up with sqlite Closes #4245

lib/transaction.js

@@ -230,9 +230,9 @@ Transaction.prototype.setIsolationLevel = function() {
 };
 
 Transaction.prototype.cleanup = function() {
+  var res = this.sequelize.connectionManager.releaseConnection(this.connection);
   this.connection.uuid = undefined;
-
-  return this.sequelize.connectionManager.releaseConnection(this.connection);
+  return res;
 };
 
 Transaction.prototype.$clearCls = function () {