title: Yarn can't find private Github npm registry
body: <p>I signed up for the Github private npm registry beta and followed their instruction: <a href="https://github.com/features/package-registry" rel="noreferrer">https://github.com/features/package-registry</a></p>
  
  <p>Works great with npm but I'd prefer using yarn. And while npm has no issues finding the registered package, yarn can't find it at all.</p>
  
  <p><code>yarn add @omniphx/adminite-adminite-ui-components</code> outputs:</p>
  
  <pre><code>yarn add v1.19.0
  info No lockfile found.
  warning package-lock.json found. Your project contains lock files generated by tools other than Yarn. It is advised not to mix package managers in order to avoid resolution inconsistencies caused by unsynchronized lock files. To clear this warning, remove package-lock.json.
  [1/4]   Resolving packages...
  error Couldn't find package "@omniphx/adminite-ui-components" on the "npm" registry.
  info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.
  </code></pre>
  
  <p>After reading up on private repos with yarn, I thought the trick was due to yarn having a slightly different rc format. Unfortunately, that didn't work either and yarn is still unable to find the private registry.</p>
  
  <p><strong>.npmrc</strong></p>
  
  <pre><code>registry=https://registry.npmjs.org
  @omniphx:registry=https://npm.pkg.github.com/omniphx
  </code></pre>
  
  <p><strong>.yarnrc</strong></p>
  
  <pre><code>registry "https://registry.npmjs.org"
  "@omniphx:registry" "https://npm.pkg.github.com/omniphx"
  </code></pre>
  
  <p>Also confirmed that my github token is set too with <code>yarn config list</code>:</p>
  
  <pre><code>yarn config v1.19.0
  info yarn config
  {
    'version-tag-prefix': 'v',
    'version-git-tag': true,
    'version-commit-hooks': true,
    'version-git-sign': false,
    'version-git-message': 'v%s',
    'init-version': '1.0.0',
    'init-license': 'MIT',
    'save-prefix': '^',
    'bin-links': true,
    'ignore-scripts': false,
    'ignore-optional': false,
    registry: 'https://registry.npmjs.org',
    'strict-ssl': true,
    'user-agent': 'yarn/1.19.0 npm/? node/v12.11.1 darwin x64',
    email: 'mattjmitchener@gmail.com',
    lastUpdateCheck: 1570679687836,
    username: 'omniphx',
    '@omniphx:registry': 'https://npm.pkg.github.com/omniphx'
  }
  info npm config
  {
    '//npm.pkg.github.com/:_authToken': 'fake12345',
    registry: 'https://registry.npmjs.org',
    '@omniphx:registry': 'https://npm.pkg.github.com/omniphx',
    python: '/usr/bin/python'
  }
  </code></pre>
  
  <p>Any idea?</p>
  
  <hr>
  
  <p><strong>Resolved</strong></p>
  
  <pre><code>Changed "@myorg:registry" "https://npm.pkg.github.com/myorg"
  To      "@myorg:registry" "https://npm.pkg.github.com"
  </code></pre>