title: Every yarn command gives "error ../package.json: Name contains illegal characters"
body: <p>Kia ora! I'm trying to install ghost-blog locally, but am running into an issue during install. It stops at "installing dependencies", and yarn install --no-emoji -no-progress (the command generated by ghost-cli) pulls an error: "../../../../package.json: Name contains illegal characters".</p>
  
  <p>I've since then noticed that almost every yarn command (except yarn --version) gives the same error, including yarn cache clear, which is making it really hard to troubleshoot.</p>
  
  <p>I've gone and hunted for package.json files floating around the system that might be causing it, since I read somewhere that yarn looks for the closest one, and deleted most of them - the ones remaining are part of npm packages and seem to have valid file/path names (all lower case, no spaces). I've also copied <a href="https://github.com/TryGhost/Ghost/blob/master/package.json" rel="noreferrer">Ghost's package.json</a> into the parent directory (as ghost-cli requires an empty directory to install) hoping yarn will pick that up instead, but no luck.</p>
  
  <p>I've uninstalled and reinstalled yarn (via home-brew) and ensured it's in my profile (zsh).</p>
  
  <p>Here's the output from ghost-cli-debug, unfortunately not very useful:</p>
  
  <pre><code>Debug Information:
      OS: Mac OS X, v10.15
      Node Version: v10.16.1
      Ghost-CLI Version: 1.11.0
      Environment: development
      Command: 'ghost install local'
  Message: Command failed: yarn install --no-emoji --no-progress
  error ../../../../package.json: Name contains illegal characters
  
  yarn install v1.16.0
  info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.
  
  Exit code: 1
  
  --------------- stdout ---------------
  yarn install v1.16.0
  info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.
  
  
  --------------- stderr ---------------
  error ../../../../package.json: Name contains illegal characters
  </code></pre>
  
  <p>Any help would be greatly appreciated! I've done a bunch of searching but can't seem to find any similar issues.</p>