updated on 2019-06-15
$ npm install -g heroku
すると...
npm WARN deprecated heroku-cli@7.0.9: 'heroku-cli' has been renamed 'heroku'
npm WARN deprecated cross-spawn-async@2.2.5: cross-spawn no longer requires a build toolchain, use it instead
'heroku-cli' は 'heroku' に変わったのでそっちを使えとさ。
1...$ npm uninstall -g heroku-cli 2...$ npm i -g heroku
完