'Make sure CONTENT_LAST gets updated only when content is written.'

def testAFF4ImageContentLastUpdated(self):

    path = '/C.12345/contentlastchecker'
    self.WriteImage(path, timestamp=1)
    fd = aff4.FACTORY.Open(path, token=self.token)
    self.assertEqual(int(fd.GetContentAge()), 101000000)
    self.WriteImage(path, timestamp=2)
    fd = aff4.FACTORY.Open(path, token=self.token)
    self.assertEqual(int(fd.GetContentAge()), 102000000)
