async cherryPickWithMessage(localBranch: string, commit: string, message: string) {
  const theirCommit = await this.repo.getCommit(commit);
  const ourCommit = await this.repo.getBranchCommit(localBranch);
  const base = await Git.Merge.base(this.repo, theirCommit.id(), ourCommit.id());

  // nodegit has a bug that causes .parent() to return a "partial" commit that
  // cannot be used for subsequent operations such as .getTree(). See
  // https://github.com/nodegit/nodegit/pull/1110.
  const baseTreeId = await theirCommit.parent(0).then(c => c.treeId());
  const baseTree = await this.repo.getTree(baseTreeId);
  const theirTree = await theirCommit.getTree();
  const ourTree = await ourCommit.getTree();
  // This does not work.
  const index = await Git.Merge.trees(this.repo, baseTree, ourTree, theirTree, null);
  const newTreeId = await index.writeTree();

  const ownCommitterSignature = theirCommit.committer(); // TODO
  return await this.repo.createCommit(localBranch, theirCommit.author(), ownCommitterSignature, message, newTreeId, [ourCommit]).then(id => id.tostrS());
}