title: How do you setup a webhook from bitbucket to AWS Codebuild to trigger only on merge to dev branch?
body: <p>AWS codebuild using Bitbucket source:</p>
  
  <p>Under "Primary source webhook events Info"</p>
  
  <p>and then under: "Start a build under these conditions"</p>
  
  <p>How do you setup the HEAD_REF and BASE_REF properly to trigger a build only on a merge from any branch to the dev branch? </p>
  
  <p>I have tried <code>^refs/heads/dev$</code> in the BASE_Ref field, but that didn't work. I have also confirmed that codebuild is connecting to bitbucket: </p>
  
  <p><code>{
    "response": "No build triggered for specified payload",
    "statusCode": 200
  }</code></p>