[headers-normalize-response.htm]
  type: testharness
  [Header value: hello_world\\0]
    expected: FAIL

  [Header value: \\0hello_world]
    expected: FAIL

  [Header value: hello_world[tab\]]
    expected: FAIL

  [Header value: [tab\]hello_world[tab\]]
    expected: FAIL

  [Header value: hello_world__]
    expected: FAIL

  [Header value: __hello_world__]
    expected: FAIL