Keep Your Head Up, Kid: The Don Cherry Story scored 1,380,000 viewers Sunday according to BBM Canada overnight estimates. Part One of the two-part CBC bio-pic (starring Jared Keeso, right) was in tough at 8 p.m. against CBS/CTV powerhouse The Amazing Race (2,470,000) and at 9 strong newcomer Undercover Boss (1,658,000). On Global, Grapes faced