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Yes, I think that is considered a bug. I think it has been reported, but I don't know about the status.
For now, you just have to avoid making closed paths when you have a Shape option set (such as ellipse shape). It's entirely possible to have the beginning and ending nodes precisely on top of each other, without joining them (which closes the path). When you draw the path, end it without closing. Then switch to the Node tool, and you can snap the nodes together. Or use some other method to put them on top of each other.
