Forms are rendered mulitple times

[gpruss]

When a user task with form input is cancelled and executed again, the form is rendererd twice, thrice, etc. until the CLI runs out of space and raises an error: "addwstr() returned ERR". If the form is present multiple times it is bound to fail validation.

To "reset" the form, it is necessary to cancel the user task, save the progress (if desired), quit out of the CLI and restart it.