Git tag is created on PR

Hi :)
I started using this action in one of my projects and I really like it so far!
One issue came up thought:

My CI configuration looks like this:

on:
  push:
    branches: [ 'main' ]
  pull_request:
    branches: [ 'main','dev' ]

  get-version:
    name: 'Get Version'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Bump version and push tag
        id: tag_version
        uses: mathieudutour/github-tag-action@v5.6
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          release_branches: main

  build-stuff:
    name: 'Build and Push Docker Images'
    needs: [ get-version ]
    runs-on: ubuntu-latest        
    ... 

So the job runs on all pushes to main and all PRs into main and dev. The README states:

release_branches (optional) - Comma separated list of branches (JavaScript regular expression accepted) that will generate the release tags. Other branches and pull-requests generate versions postfixed with the commit hash and do not generate any repository tag.

So I would expect the action to output a value for new_version, but not create a new tag in the repository. However a new tag is being created on PRs.

Any help on this would be appreciated 😀

Start by reproducing the workflow from the issue with both push and pull_request triggers, using release_branches set to main. Inspect the action's handling of pull requests and branch matching; done means pull requests produce new_version without creating a repository tag, while pushes to main retain tagging behavior.