TestImpalaShellInteractive.test_http_interactions_extra fails on Python 3

[gw2] linux2 -- Python 2.7.16 /home/joe/view2/Impala/bin/../infra/python/env-gcc7.5.0/bin/python
self = <tests.shell.test_shell_interactive.TestImpalaShellInteractive object at 0x7fe5b9dacb50>
vector = <tests.common.test_vector.ImpalaTestVector object at 0x7fe5ba153dd0>
http_503_server_extra = <tests.shell.test_shell_interactive.TestHTTPServer503 object at 0x7fe5b9dacbd0>    def test_http_interactions_extra(self, vector, http_503_server_extra):
      """Test interactions with the http server when using hs2-http protocol.
        Check that the shell prints a good message when the server returns a 503 error,
        including the body text from the message."""
      protocol = vector.get_value("protocol")
      if protocol != 'hs2-http':
        pytest.skip()
    
      # Check that we get a message about the 503 error when we try to connect.
      shell_args = ["--protocol={0}".format(protocol),
                    "-i{0}:{1}".format(http_503_server_extra.HOST,
                                       http_503_server_extra.PORT)]
      shell_proc = spawn_shell([IMPALA_SHELL_EXECUTABLE] + shell_args)
>     shell_proc.expect("HTTP code 503: Service Unavailable \[EXTRA\]", timeout=10)shell/test_shell_interactive.py:1201: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
../infra/python/env-gcc7.5.0/lib/python2.7/site-packages/pexpect/__init__.py:1451: in expect
    timeout, searchwindowsize)
../infra/python/env-gcc7.5.0/lib/python2.7/site-packages/pexpect/__init__.py:1466: in expect_list
    timeout, searchwindowsize)