function buildVersion(packageVersion, sha, channel) {
  let base = semver.parse(packageVersion);
  let major = base.major;
  let minor = base.minor;
  let patch = base.patch;
  let suffix = '';
  suffix += toSuffix('-', base.prerelease, channel);
  suffix += toSuffix('+', base.build, sha);
  return `${major}.${minor}.${patch}${suffix}`;
}
@param {string} packageVersion
@param {string} sha
@param {string=} channel