title: Github action evaluating false as true
body: <p>I have an action like this</p>
  <pre><code>  - name: &quot;Set flag&quot;
      id: &quot;setMap&quot;
      env:
        SOURCE_MAP_VAR: ${{ contains(github.event.head_commit.message, '--sm') }}
      run: |
        if ($env:SOURCE_MAP_VAR) {
          echo &quot;::set-output name=S_F::--sm&quot;
        } else {
          echo &quot;::set-output name=S_F::&quot;
        }
  
    - name: Yarn build
      run: yarn run build ${{ steps.setSMap.outputs.S_F }}
  </code></pre>
  <p>even the SOURCE_MAP_VAR is evaluating as false but it still sets the --sm flag, here is the output:</p>
  <pre><code>  if ($env:SOURCE_MAP_VAR) {
      echo &quot;::set-output name=S_F::--sm&quot;
    } else {
      echo &quot;::set-output name=S_F::&quot;
    }
    shell: C:\Program Files\PowerShell\7\pwsh.EXE -command &quot;. '{0}'&quot;
    env:
      NODE_OPTIONS: --max_old_space_size=4096
      SOURCE_MAP_VAR: false
  ...
    yarn run build --sm   
  </code></pre>