When a mob stand between 2 normal block, another mob cannot avoid it when finding path.

I think this bug should have existed for a long time, not just in this version. 
When a mob stand between 2 normal block, another mob cannot avoid it when finding path. For example, I use fence surround a villager and stand between 2 normal block (not fence). I spawn a husk, but the husk cannot avoid me and push me to find the villager. It can also occur when I try to use other mob.