Forbes v. State, 96 Nev. 17, 604 P.2d 799 (1980). On the other hand, in Founts v. Warden, 91 Nev. 353, 535 P.2d 1291 (1975), we suggested that the provision would apply to a defendant who commits a felony while on parole. Appellant relies on Van Dorn v. Warden, 93 Nev. 524, 569 P.2d 938 (1977) for his contention that a person who is on probation should not be considered "a person under sentence of imprisonment.