title: How to undo a merge on Bitbucket?
body: <p>I've created a merge (into the 'master' branch) that's now on a Bitbucket repo. Long story short: I need to undo that merge. </p>
  
  <p>I know that you can do this at the Github site itself, but Bitbucket doesn't have that feature. I'm not clear on how to do this with Git without causing a mess.</p>