title: Why does `yarn global add` fail but `yarn add` succeed?
body: <p>I'm trying to install <code>babel-preset-env</code> on a Mac, but when I try to install it globally with yarn it fails. What's going on?</p>
  
  <pre><code>$ yarn global add babel-preset-env
  yarn global v1.7.0
  warning package.json: No license field
  [1/4]   Resolving packages...
  ⠂ babel-preset-env(node:11264) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
  [2/4]   Fetching packages...
  [3/4]   Linking dependencies...
  [4/4]   Building fresh packages...
  warning "babel-preset-env@1.7.0" has no binaries
  ✨  Done in 1.26s.
  
  $ yarn add babel-preset-env
  yarn add v1.7.0
  warning package.json: No license field
  warning No license field
  [1/4]   Resolving packages...
  ⠁ (node:11273) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
  [2/4]   Fetching packages...
  [3/4]   Linking dependencies...
  [4/4]   Building fresh packages...
  success Saved lockfile.
  success Saved 62 new dependencies.
  info Direct dependencies
  └─ babel-preset-env@1.7.0
  info All dependencies
  ├─ ansi-styles@2.2.1
  ├─ babel-code-frame@6.26.0
  ├─ babel-helper-builder-binary-assignment-operator-visitor@6.24.1
  ├─ babel-helper-call-delegate@6.24.1
  ├─ babel-helper-define-map@6.26.0
  ├─ babel-helper-explode-assignable-expression@6.24.1
  ├─ babel-helper-remap-async-to-generator@6.24.1
  ├─ babel-plugin-check-es2015-constants@6.22.0
  ├─ babel-plugin-syntax-async-functions@6.13.0
  ├─ babel-plugin-syntax-exponentiation-operator@6.13.0
  ├─ babel-plugin-syntax-trailing-function-commas@6.22.0
  ├─ babel-plugin-transform-async-to-generator@6.24.1
  ├─ babel-plugin-transform-es2015-arrow-functions@6.22.0
  ├─ babel-plugin-transform-es2015-block-scoped-functions@6.22.0
  ├─ babel-plugin-transform-es2015-block-scoping@6.26.0
  ├─ babel-plugin-transform-es2015-classes@6.24.1
  ├─ babel-plugin-transform-es2015-computed-properties@6.24.1
  ├─ babel-plugin-transform-es2015-destructuring@6.23.0
  ├─ babel-plugin-transform-es2015-duplicate-keys@6.24.1
  ├─ babel-plugin-transform-es2015-for-of@6.23.0
  ├─ babel-plugin-transform-es2015-function-name@6.24.1
  ├─ babel-plugin-transform-es2015-literals@6.22.0
  ├─ babel-plugin-transform-es2015-modules-amd@6.24.1
  ├─ babel-plugin-transform-es2015-modules-commonjs@6.26.2
  ├─ babel-plugin-transform-es2015-modules-systemjs@6.24.1
  ├─ babel-plugin-transform-es2015-modules-umd@6.24.1
  ├─ babel-plugin-transform-es2015-object-super@6.24.1
  ├─ babel-plugin-transform-es2015-parameters@6.24.1
  ├─ babel-plugin-transform-es2015-shorthand-properties@6.24.1
  ├─ babel-plugin-transform-es2015-spread@6.22.0
  ├─ babel-plugin-transform-es2015-sticky-regex@6.24.1
  ├─ babel-plugin-transform-es2015-template-literals@6.22.0
  ├─ babel-plugin-transform-es2015-typeof-symbol@6.23.0
  ├─ babel-plugin-transform-es2015-unicode-regex@6.24.1
  ├─ babel-plugin-transform-exponentiation-operator@6.24.1
  ├─ babel-plugin-transform-regenerator@6.26.0
  ├─ babel-plugin-transform-strict-mode@6.24.1
  ├─ babel-preset-env@1.7.0
  ├─ browserslist@3.2.8
  ├─ caniuse-lite@1.0.30000852
  ├─ chalk@1.1.3
  ├─ core-js@2.5.7
  ├─ debug@2.6.9
  ├─ electron-to-chromium@1.3.48
  ├─ escape-string-regexp@1.0.5
  ├─ globals@9.18.0
  ├─ has-ansi@2.0.0
  ├─ js-tokens@3.0.2
  ├─ jsesc@0.5.0
  ├─ loose-envify@1.3.1
  ├─ ms@2.0.0
  ├─ private@0.1.8
  ├─ regenerate@1.4.0
  ├─ regenerator-runtime@0.11.1
  ├─ regenerator-transform@0.10.1
  ├─ regexpu-core@2.0.0
  ├─ regjsgen@0.2.0
  ├─ regjsparser@0.1.5
  ├─ semver@5.5.0
  ├─ strip-ansi@3.0.1
  ├─ supports-color@2.0.0
  └─ to-fast-properties@1.0.3
  warning No license field
  ✨  Done in 2.62s.    
  </code></pre>