code: function updateMaster () {
      pushCmds.push(
          comment('update package.json in master'),
          'git checkout master',
          `git pull --rebase ${origin} master --strategy=theirs`,
          `git checkout release/${newVersion} -- CHANGELOG.md`,
          `node -e "const newVersion = '${newVersion}'; ${stringifyFunction(buildCommand)}"`,
          'git add CHANGELOG.md',
          'git add package.json',
          `git commit -m "update version number in package.json to ${newVersion}"`,
          `git push ${origin} master`
      );
  
      function buildCommand () {
        require('fs').writeFileSync('package.json', JSON.stringify(getUpdatedJson(), null, 2));
        function getUpdatedJson () {
          const json = require('./package.json');
          json.version = newVersion;
          return json;
        }
      }
  
      function stringifyFunction (method) {
        return method
            .toString()
            .split('\n')
            .slice(1, -1)
            .map(function (line) { return line.trim(); })
            .join(' ')
            .replace(/"/g, '\\"');
      }
    }
docs: copies the changelog back over to master branch