message: fix script/npm-prepack
  Looks like globby requires a cwd option (?), and fs-extra's exists()
  function is now called pathExists() (though there's an alias, it's good
  to be on the official API).
diff: @@ -57,7 +57,7 @@ run('npm', ['-s', '--ignore-scripts', 'pack', '--json'])
  mustHave(config.required),
  mustLack(config.missing)
  ]))
  - .catch(err => die(err.message))
  + .catch(err => die(err))
  .then(() => {
  if (dir) {
  log(`removing: ${dir}`)
  @@ -78,18 +78,20 @@ function die(...args) {
  process.exitCode = 1
  }
  -function mustHave(globs) {
  - return Promise.all(globs.map(fse.exists)).then(results => {
  - const missing = results.map((exists, i) => ({glob: globs[i], exists}))
  +function mustHave(paths) {
  + return Promise.all(paths.map(fse.pathExists)).then(results => {
  + const missing = results.map((exists, i) => ({path: paths[i], exists}))
  .filter(res => !res.exists)
  if (missing.length > 0) {
  - throw new Error(`Missing files:${list(missing.map(d => d.glob))}`)
  + throw new Error(`Missing files:${list(missing.map(d => d.path))}`)
  }
  })
  }
  function mustLack(globs) {
  - return Promise.all(globs.map(globby)).then(results => {
  + const globOptions = {cwd: process.cwd()}
  + const promises = globs.map(pattern => globby(pattern, globOptions))
  + return Promise.all(promises).then(results => {
  const found = results.map((matches, i) => ({glob: globs[i], matches}))
  .filter(res => res.matches.length > 0)
  if (found.length > 0) {
  