message: Use prBranch when available
diff: @@ -73,20 +73,21 @@ export async function getCommitAndBranch({ inputFromCI } = {}) {
  // On certain CI systems, a branch is not checked out
  // (instead a detached head is used for the commit).
  if (branch === 'HEAD' || !branch) {
  - ({ branch } = envCi());
  - if (branch === 'HEAD' || !branch) {
  + const { prBranch: prBranchFromEnvCi, branch: branchFromEnvCi } = envCi();
  +
  // $HEAD is for netlify: https://www.netlify.com/docs/continuous-deployment/
  // $GERRIT_BRANCH is for Gerrit/Jenkins: https://wiki.jenkins.io/display/JENKINS/Gerrit+Trigger
  // $CI_BRANCH is a general setting that lots of systems use
  branch =
  + prBranchFromEnvCi ||
  process.env.HEAD ||
  process.env.GERRIT_BRANCH ||
  process.env.CI_BRANCH ||
  process.env.GITHUB_REF ||
  + branchFromEnvCi ||
  branch ||
  'HEAD';
  }
  - }
  // REPOSITORY_URL is for netlify: https://www.netlify.com/docs/continuous-deployment/
  const fromCI = inputFromCI || !!process.env.CI || !!process.env.REPOSITORY_URL;
  debug(
  