title: Manually failing a build after it's complete
body: <p>Is it possible to set the build result for a build after that build is complete? </p>
  
  <p>I could not find any plugins that do this already, and I was considering writing my own, but I wanted to see if this was even possible before going down that path. </p>
  
  <p>(I have looked at existing code and how the "Fail The Build" plugin works as an example, but my understanding of the Jenkins code base is not advanced enough to understand what all the possibilities are.)</p>
  
  <p>Use case: we have a build pipeline, and near the end of the pipeline there is a deploy-to-qa step that deploys the artifact to a QA environment. We have automated tests before this step to try to catch any problems with the artifact, but our test coverage is not very high in some areas so bugs could still slip through the cracks. I'd like to have the ability to mark a deploy-to-qa build as FAILED after the fact, to denote that that particular pipeline was invalid and is not a candidate for production release. (Basically the same as <a href="http://code.google.com/p/build-pipeline-plugin/issues/detail?id=101" rel="nofollow">this Build Pipeline Plugin issue</a>)</p>