In the Good Old Summertime — a tale of squabbling music-shop clerks who don’t know they’re romantic pen pals — shares a celebrated movie lineage that includes James Stewart and Margaret Sullavan in The Shop Around the Corner and Tom Hanks and Meg Ryan in You’ve Got Mail. In between those two, Judy Garland and Van Johnson had mail plus Gold Old tunes evoking an era of straw boaters and silvery moons. Sparked by Garland’s comedic zest and musical appeal, this confection is “one of the sweetest, most unpretentious entertainments of 1949” (Clive Hirschhorn, The Hollywood Musical). It’s also a nostalgic farewell and a sunny hello. Buster Keaton appears in his final film for the studio he first joined in 1928. And Liza Minnelli, all of 18 months young, makes her debut in the finale.