Bob Wills lyrics: the verse "My Old Missus ...set me free" occurs in many variations in Negro songs. "Chicken in the breadpan" is another floating or borrowed verse.
One of the many "set me free" verses, this one from Newman L. White, 1928, American Negro Folk-Songs, reported from Alabama, 1915.
My ole mistis promised me
When she died she'd set me free.
She lived so long
That her head got ball,
And the Lord couldn't kill her with a hickory maul.

Also this one from Alabama, 1915 (same reference):
Chicken in the bread tray
Scratching out dough;
Sally, will your dog bite?
No, child, no.

There are innumerable verses of this type, sung by both Negroes and Whites, and used in play-parties by children and adults. They pop up wherever a filler verse in needed.