title: Azure DevOps cancells some pipelines when exlusive lock with sequential run is enabled
body: <p>According to documentation I can now use sequential deployments with usage of <code>lockBehavior: sequential</code> and exclusive locks on environment.</p>
  <p>It works fine, stages that want to deploy to certain environment are queued and waiting for lock to be acquired but sometimes they are simply cancelled with information <code>Did not obtain the lock</code> like in the screen below. It happens randomly. When I rerun the pipeline again - sometimes it success sometimes fails with the same message. What could be the reason of cancelling these pipelines?</p>
  <p><a href="https://i.stack.imgur.com/oX9Uc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oX9Uc.png" alt="enter image description here" /></a></p>
  <p>Infromation about sequential deployments:
  <a href="https://docs.microsoft.com/en-us/azure/devops/release-notes/2021/sprint-190-update" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/azure/devops/release-notes/2021/sprint-190-update</a></p>