You can open containers which are inside a claim but on the edge of the claim from outside of the claim, however you get negative karma for doing so (I don't know if you would get more negative karma if you took anything - I didn't try).
I figure even if being able to open the containers isn't a bug, getting the negative karma for opening something which you can reach without going into the claim might be. At the very least, getting negative karma for not stealing should be a bug.