message: Fully fix macos py39 builds
diff: @@ -24,8 +24,8 @@ export DEVELOPER_DIR=/Applications/Xcode_10.3.app/Contents/Developer
  sudo xcode-select -s "${DEVELOPER_DIR}"
  # Set up py39 via pyenv and check it worked
  -PY_VERSION=3.9.1
  -setup_python_from_pyenv_macos "${PY_VERSION}"
  +export PYENV_VERSION=3.9.1
  +setup_python_from_pyenv_macos "${PYENV_VERSION}"
  # Set up and install MacOS pip dependencies.
  install_macos_pip_deps
  @@ -42,7 +42,7 @@ yes "" | "$PYTHON_BIN_PATH" configure.py
  # Export optional variables for running pip.sh
  # Pass PYENV_VERSION since we're using pyenv. See b/182399580
  -export TF_BUILD_FLAGS="--config=release_cpu_macos --action_env PYENV_VERSION=${PY_VERSION}"
  +export TF_BUILD_FLAGS="--config=release_cpu_macos --action_env PYENV_VERSION=${PYENV_VERSION}"
  export TF_TEST_FLAGS="--define=no_tensorflow_py_deps=true --test_lang_filters=py --test_output=errors --verbose_failures=true --keep_going --test_env=TF2_BEHAVIOR=1"
  export TF_TEST_TARGETS="//tensorflow/python/..."
  export TF_PIP_TESTS="test_pip_virtualenv_non_clean test_pip_virtualenv_clean"
  