title: How to run pipeline only on pull request to master branch
body: <p>Bitbucket pipelines allows to define checks on pull-requests and has glob filter that allows checking source branch. </p>
  
  <pre><code>pipelines:
    pull-requests:
      '**': #this runs as default for any branch not elsewhere defined
        - step:
            script
              - ...
      feature/*: #any branch with a feature prefix
        - step:
            script:
              - ...
  </code></pre>
  
  <p>How to filter based on target branch? There are some tests that need to be done only when merging into master.</p>