Unexpected node_modules when installing Bower dependencies

[tony19]

Bug

Running yarn on a project that only has a bower.json (no package.json) results in both bower_components/ and node_modules/.

bower.json:

{
  "name": "polymer-starter-kit",
  "authors": [
    "The Polymer Authors"
  ],
  "private": true,
  "dependencies": {
    "app-layout": "PolymerElements/app-layout#^0.10.0",
    "app-route": "PolymerElements/app-route#^0.9.0",
    "iron-flex-layout": "PolymerElements/iron-flex-layout#^1.0.0",
    "iron-icon": "PolymerElements/iron-icon#^1.0.0",
    "iron-iconset-svg": "PolymerElements/iron-iconset-svg#^1.0.0",
    "iron-localstorage": "PolymerElements/iron-localstorage#^1.0.0",
    "iron-media-query": "PolymerElements/iron-media-query#^1.0.0",
    "iron-pages": "PolymerElements/iron-pages#^1.0.0",
    "iron-selector": "PolymerElements/iron-selector#^1.0.0",
    "paper-icon-button": "PolymerElements/paper-icon-button#~1.1.0",
    "polymer": "Polymer/polymer#^1.6.0",
    "neon-animation": "^1.2.4"
  },
  "devDependencies": {
    "web-component-tester": "^4.0.0"
  }
}

The resulting node_modules/ directory contains:

$ ls node_modules 
sinon-chai

Steps to reproduce

1. Copy the bower.json contents above into a local file.
2. Run yarn (version 0.15.1).

Expected behavior

Only bower_components/ installed when yarn is run

Versions

• node.js 6.7.0
• macOS Sierra 10.12
• yarn 0.15.1

[tony19]

Workaround:

yarn install --modules-folder bower_components

[wyze]

Bower support has been dropped in #1441.