(b) No proceeding in which an accused has been found guilty by a court-martial upon any charge or specification is a trial in the sense of this section until the finding of guilty has become final after review of the case has been fully completed. However, a proceeding which, after the introduction of evidence but before a finding, is dismissed or terminated by the convening authority, or on motion of the prosecution for failure of available evidence or witnesses without any fault of the accused, is a trial in the sense of this section.