Well, if this thread is still alive!
With Macron (En Marche!) winning the French election I remembered much of the 1st verse at least of this Carol. It was taught to us by our French teacher at school, must have been 40 years ago!
I got as far as j'ai rencontre le diable so Trevor has kindly provided the next line.
It follows with la-la-la, la-la-la-la j'ai rencontre le diable and a final line which I don't remember. But it fits the same metre as je l'ai bien reconnect.
I do remember the tune and was singing it when I looked up more in hope than expectation on google.
It translates as:
As I was going to the stable
Where baby Jesus was asleep
I met the devil
I recognised him well (or more loosely, easily).

Beyond that I have no memory but devil was trying to join the journey to meet Jesus (I think) and somehow the story ended happily.