Moved fence disconnects leads

Last time I reported a bug, it was a duplicate.
This time, I searched a bit, but I don't think someone else posted it, so I take a chance.
I apologize if this is not a bug, but here is the problem:
As seen in the first image, I attach a bunch of animals (here, tasty chickens) to a barrier by some leashes.
Then, I say to myself "Hey, it would be awesome if animals could be moved automatically by pistons just by their barrier! Lets test it!".
And then, as seen in the second image, I push the barrier with some piston, but...The leashes all break, and tasty chicken fall into hole of doom.

So here is the situation: Is it a bug, or does it work as intended?
If it is a bug, then: Save the future tasty chikens! :'(
If it works as intended...Sorry again.

Have a good day, reader!

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