Skeleton not die in morning

So, i'm not know, old this bug, or new, but him exist. Okey, yesterday i'm and my sister playing on my world. Just survive. Okey, we just funniest)). So,night falls and we go to my house. And in morning, we see that: skeleton just stay on semi-block and not die.  Why??  

 

 

 

 

SORRY, I'M RUSSIAN. MY ENGLISH SO BED!