Unlock button is always displayed to node owner

Add patch from MR.

But isn't it reasonable that you have option to unlock the content you are editing? It's almost like a "cancel edit button". The problem wold be if you want to break someone elses lock. And than permission would be needed.
But I don't think this change is needed as you should be able to unlock the content you just locked.

In an environment where you have someone proposing content and other users managing this content, it’s common need that you don’t want these first users to confuse them with an unlock button. This might not be a permission but an alter hook. Whatever suits you best.