Function getReleaseNotesDraft

scripts/release_notes/util.ts:132–242

(
    octokit: OctokitGetCommit, repoCommits: RepoCommits[])

 * @returns The release notes markdown draft as a string.
 */
export async function getReleaseNotesDraft(
    octokit: OctokitGetCommit, repoCommits: RepoCommits[]): Promise<string> {
  const repoNotes: string[] = [];
  for (let i = 0; i < repoCommits.length; i++) {
    const repoCommit = repoCommits[i];

    const getUsernameForCommit = async (sha: string) => {
      let result;
      try {
        result = await octokit.repos.getCommit(
            {owner: 'tensorflow', repo: 'tfjs', sha});
        return result.data.author.login;
      } catch (e) {
        console.log(`Error fetching username for commit ${sha}`);
        console.log(`Using ${result.data.commit.author.name}`);
        return result.data.commit.author.name;
      }
    };

    const tagEntries: {[tag: string]: string[]} = {};
    SECTION_TAGS.forEach(({tag}) => tagEntries[tag] = []);

    for (let j = 0; j < repoCommit.commits.length; j++) {
      const commit = repoCommit.commits[j];

      const tagsFound: Array<{tag: string, tagMessage: string}> = [];
      const bodyLines = commit.body.split('\n').map(line => line.trim());
      // Get tags for the body by finding lines that start with tags. Do
      // this without a regex for readability.
      SECTION_TAGS.forEach(({tag}) => {
        if (tag === 'INTERNAL') {
          return;
        }

        bodyLines.forEach(line => {
          // Split by word boundaries, and make sure the first word is the
          // tag.
          const split = line.split(/\b/);
          if (split[0] === tag) {
            const tagMessage = line.substring(tag.length).trim();
            tagsFound.push({tag, tagMessage});
          }
        });
      });
      // If no explicit tags, put this under misc.
      if (tagsFound.length === 0) {
        tagsFound.push({tag: 'MISC', tagMessage: ''});
      }

      const username = await getUsernameForCommit(commit.sha);
      const isExternalContributor =
          !commit.authorEmail.endsWith('@google.com') &&
          !isGooglerUsername(username);

      const pullRequestRegexp = /\(#([0-9]+)\)/;
      const pullRequestMatch = commit.subject.match(pullRequestRegexp);

      let subject = commit.subject;