title: I merged a pull request and GitHub automatically merged another one
body: <p>I am experiencing an odd issue with GitHub and would like to know if it is by design. I merge a pull request and sometimes a separate pull request also gets merged. This seems to happen automatically. I've noticed, for the pull request that gets auto-merged by GitHub, its branch was merged into the branch of the pull request that I merged manually. </p>
  
  <p>So, for example, I have branch <code>A</code>, which I am merging a PR for. I merge another branch, branch <code>B</code>, into branch <code>A</code> before merging the PR for branch <code>A</code>. I then merge the PR for branch <code>A</code>, and the PR for branch <code>B</code> is automatically merged.</p>
  
  <p><strong>Is this by design?</strong> It doesn't make any sense to me. Why would GitHub assume that branch <code>B</code> is ready to be merged into <code>dev</code> just because I merged it into branch <code>A</code>? In our team, we merge branches into each other to minimize conflicts when PRs are merged. I'd also like to know if it is possible to change this behavior somewhere in GitHub.</p>