message: ci: only lint commit messages on PRs
  As all commit messages are linted during the PR process, we
  do not need to relint these previous commit messages on upstream
  branches.
  PR Close
diff: // tslint:disable:no-console
  module.exports = (gulp) => () => {
  try {
  + if (process.env['CIRCLECI'] === 'true' && !process.env['CIRCLE_PR_NUMBER']) {
  + console.info(
  + `Since commit messages are validated as part of the PR review process,\n` +
  + `we do not need to commit messages on CI runs on upstream branches.\n\n` +
  + `Skipping validate-commit-message check`
  + )
  + process.exit();
  + }
  const validateCommitMessage = require('../validate-commit-message');
  const shelljs = require('shelljs');
  