I have had this happen once.
Back several years ago when I was still feeding live (have gotten him to switch to f/t) my bp Nicky must have been verry hungery as he only constricted that weeks meal till it passed out. He started swallowing it and it came to with its back legs still sticking out of his mouth. I could see it kick its legs and move through his skin but it did not seem to bother Nicky in the least. He just kept swallowing and had no problems.
I recomend always trying to switch snakes to pree killed or f/t to avoid any risk of injury.
A
-----
1.0 normal BP Nicodemus
1.0 BP Moufasa pos vanilla, fire, cinny
0.4 Cal Kings 3 alb 1 het Dora Queen Ace Pearl
2.0 Alb Corn Bizaar Elixir
0.0.1 Rev Alb Nelsons Oden