ui/termstatus: fix clearing status lines

To clear the status lines, they should be set to an empty array to
prevent future updates of those lines. Setting the status lines to an
array containing an empty string is wrong as this causes the output to
continuously add that empty status line after each message.

cmd/restic/progress.go

@@ -53,7 +53,7 @@ func newGenericProgressMax(show bool, max uint64, description string, print func
 func newTerminalProgressMax(show bool, max uint64, description string, term *termstatus.Terminal) *progress.Counter {
 	return newGenericProgressMax(show, max, description, func(status string, final bool) {
 		if final {
-			term.SetStatus([]string{})
+			term.SetStatus(nil)
 			term.Print(status)
 		} else {
 			term.SetStatus([]string{status})