Julien Danjou 8b73a963c3 Fix BaseMeta with six >= 1.4.0
A change in six broke this code; sometimes there is no bases at all.

Change-Id: I7b86f6e4aac61cfd313e42bc26b5e6b27e4e9555
2013-09-02 11:18:40 +02:00
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2013-09-02 11:18:40 +02:00