Avoid repeating pipeline steps when tag AND commit

here is my drone.io pipeline:

matrix:
  NODE_TAG:
    - 9
    - 8
    - 6

pipeline:
  build:
    image: node:${NODE_TAG}
    commands:
      - npm install
      - npm test

  npm:
    image: plugins/npm
    when:
      event: tag
      matrix:
        NODE_TAG: 6

But when I tag and push to repo, it runs 2 times the build step.

Any way to avoid repeating two times this costly build step when commiting a tag ?

Many thanks!

Hello there, any input in this one? Many thanks!