Actually, you all are correct. The version that charbot posted was used for the pilot, then the updated, edited version that we all know (the one that Brandon 2006 posted) was used for the first first few seasons. Then the theme gradually changed over the years to the version that TJ posted, which just has the chorus only.
"Nip it in the bud!!"
Words made famous by Barney Fife on The Andy Griffith Show