title: "This branch has conflicts that must be resolved" but it's already merged
body: <p>I merged a <a href="https://github.com/DaniSchenk/moment-feiertage/pull/8" rel="noreferrer">PR</a> with the GitHub web interface, which resolved in a successful <a href="https://github.com/DaniSchenk/moment-feiertage/commit/6ea0b7a08c8a5b5d81f836493235ad4c55b7d0e9" rel="noreferrer">merge commit</a>.</p>
  <p>Afterwards, GitHub is complaining <em>This branch has conflicts that must be resolved</em>. Does anybody know why or how to get the status <em>merged</em>?</p>