err = s.fs.Rename("/by_id/"+fixtureFooCollection, "/by_id/beep")
c.Check(err, check.Equals, ErrInvalidArgument)
err = s.fs.Rename("/by_id/"+fixtureFooCollection+"/foo", "/by_id/beep")
err = s.fs.Rename("/by_id/"+fixtureFooCollection, "/by_id/beep")
c.Check(err, check.Equals, ErrInvalidArgument)
err = s.fs.Rename("/by_id/"+fixtureFooCollection+"/foo", "/by_id/beep")