I think the "animals escaping pens fix" was missed for sheep. On our server on 1.6.2 sheep keep escaping from our pen, even though we also have a cow, but there's never any escaping cows.

I am pretty sure that it is because of chunks reloading that makes them escape. I haven't seen them escaping when we're in the area.

I will upload screenies of the pens just in case.