'Test that a C{mkdir} on an existing directory fails with the
appropriate error, and doesn\'t log an useless error server side.'

def test_existingRemoteDirectory(self):

    def _check(results):
        self.assertEqual(results[0], '')
        self.assertEqual(results[1], 'remote    error    11:    mkdir    failed')
    d = self.runScript('mkdir    testMakeDirectory', 'mkdir    testMakeDirectory')
    d.addCallback(_check)
    return d
