title: Is it possible to close gitlab merge request by Jenkins when build fails
body: <p>It works like this now,somebody creates a merge request in gitlab which triggers a build in Jenkins through “Trigger builds remotely”,jenkins implements the defined build and does something after the build(Post-build Actions).
  There's an option called "Accept gitlab merge request on success" in the "Post-build Actions" in jenkins jobs,but we want to implement "Close/Delete gitlab merge request on failure" after a failed build,is this possible please?
  Thank you.</p>