Issued as part of Universal France's Essentials of Cinema series, Serge Gainsbourg's soundtracks to Michel Colombier's 1968 Ce Sacre Grand-Pere, and Pierre Koralnik's scandalous Cannabis, are among the most startling pieces of music in his oeuvre. Cannabis was based around a tawdry thriller and was set by Pierre Koralnik in the free, lone-generation of the late '60s, and starred none other than Gainsbourg and wife Jane Birkin…