Preview page not shown when the "previous page" button it's called "Submit"

There's an error in showing the preview page in webforms.

We have activated the option in Webform > Form settings > Preview Page but when I press the Send button it goes directly to the thanks page.

Then we found the error: In the preview's page configuration, when the "Preview button label" is set to the value "Submit", then there's a bug and the webform thinks it's the submit button and not the preview page one.

http://civicrm.stackexchange.com/questions/10392/preview-page-not-shown-in-webforms