Fix issues introduced in commit c3c2112cb1,
reported by Satoshi KOBAYASHI on ryu-devel.
Use six.moves to handle module name changes.
Signed-off-by: IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>