Cloning an element with attributes creates an empty userData attribute

[leomayer]

We have in our tests the following element

<span id="test"></span>

In our code base we check if an element has no attribute except id. This is checked by the following code

e.clone()
	.removeAttr("id")
	.attributes()
	.isEmpty()

With 1.20.1 this return true while 1.21.1 this returns false. Somehow there is still a single attribute left. I would guess it has to do with the clone but I'm not sure.

I just report it but I'm aware that there is better method for checking, e.g.

e.attributes().size()==1 & e.attributes.hasKey("id")

[jhy]

Thanks for the report; fixed!

Caused by the changes for #2334.