Fix cqlsh completion test

cqlshlib.test.test_cqlsh_completion.TestCqlshCompletion.test_complete_in_drop_keyspace (from nosetests)

Failing for the past 1 build (Since Unstable#42 )
Took 2 sec.
Error Message
Items in the second set but not the first:
'system_views'
'system_virtual_schema'
    """Fail immediately, with the given message."""
>>  raise self.failureException("Items in the second set but not the first:\n'system_views'\n'system_virtual_schema'")