HOLLYWOOD (Variety) - Disney and Jim Henson Pictures have become leashed to the singing-dog picture "Let It Rain." They've made a potential seven-figure preemptive pitch deal with writers Cinco Paul and Ken Daurio ("Bubble Boy"). "Let It Rain" (tentative title) is a live-action musical with four-legged participants. A canine con artist enters a barnyard of a drought-stricken farm and persuades the animals that singing the right songs will bring rain and end their misery. Between all the songs and hoofing, the animals grow to love and respect the strange interloper. Michael.