message: Add flags to __all__ in tensorflow v1 API.
  We eagerly initialize __all__ variable in the API template and then we make more imports. This fix just adds required names to __all__.
diff: @@ -78,6 +78,8 @@ if '__all__' in vars():
  from tensorflow.python.platform import flags # pylint: disable=g-import-not-at-top
  # The 'app' module will be imported as part of the placeholder section above.
  app.flags = flags # pylint: disable=undefined-variable
  +if '__all__' in vars():
  + vars()['__all__'].append('flags')
  # Load all plugin libraries from site-packages/tensorflow-plugins if we are
  # running under pip.
  