Fix little test errors
    
    Two test methods in test_rpcserver had the same name; the first didn't get
    to run.
    Another duplicate pair was in test_hbac_plugin with the same name; the ignored
    test had small error in it.
    check_TypeError used a wrong constant name
    An error reporting function in test.util used uninitialized argument names.
    
    This patch fixes these problems.