title: macos ${{ env.TMPDIR }} notworking in github actions
body: <p>I have a github action which tries to use ${{ env.TMPDIR }} and that doesnt appear to expand to the TMPDIR environment variable.</p>
  <pre><code> - name: DEBUG Workaround GitHub-Actions-MacOS Issue with env.TMPDIR
      run: |
        echo &quot;TMPDIR=$TMPDIR&quot;
        echo &quot;TMPDIR using ENV.TMPDIR=${{ env.TMPDIR }}&quot;
  </code></pre>
  <p>this produces:</p>
  <pre><code>TMPDIR=/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/
  TMPDIR using ENV.TMPDIR=
  </code></pre>
  <p>EXAMPLE:
  <a href="https://github.com/SophistSolutions/Stroika/runs/1508428339?check_suite_focus=true" rel="nofollow noreferrer">DEBUG Workaround GitHub-Actions-MacOS Issue with env.TMPDIR</a></p>