title: Execute a flask run in Jenkins shell without timeout
body: <p>I'm using Jenkins to run a Flask app automatically from a Git branch.
  The build works well, and it starts the Flask app on my server, except that when you run <code>flask run</code>, the command line stays active as long as the flask app runs.
  Thus, the build never ends, and it ends up as an unstable build.</p>
  
  <p>How can I get the flask app to run and get a Jenkins build success if it got the the <code>* Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)</code> message?</p>