title: Jenkins Pipeline Git commit message before scm checkout
body: <p>I would like to be able to access the commit message in a Jenkins Pipeline before the actual <code>checkout scm</code> since I have huge repositories (>2GB) and many branches (>200) and for every branch the complete repo gets cloned again and I want to limit the amount of clones by filtering the commit messages for explicit "tags" (eg <code>[ci]</code>). If you know a different approach that would solve my issue, please let me know.</p>
  
  <p>Edit: I am using scripted jenkinsfiles and shared libraries with multibranch pipelines.. so I'm looking for a way to do that programmatically :)</p>