> The trouble with putting the current task on the submit button is that the user is already doing that task and they might think that the button is a link to start the task over

Yup. Another risk is using an ambiguous phrasing, such as on this very web site: in order to post your comment, you have to click on a button that says "Leave comment".

Does this mean the button will post my comment or abandon it because I want to leave?