title: Yarn not installing in nvm version node version
body: <p>I'm running into an issue with yarn when I change my nvm version of node. 
  I noticed when I check my ~/.nvm folder I see two node versions. </p>
  
  <ul>
  <li>v8.11.0  </li>
  <li>v8.11.3.</li>
  </ul>
  
  <p>I installed yarn globally. using <strong>npm install -g yarn</strong> when I was using v8.11.0. </p>
  
  <p>I can see yarn in my </p>
  
  <pre><code>.nvm/versions/node/v8.11.0
  </code></pre>
  
  <p>But when I switch to nvm v8.11.3 or set my nvm alias default to v8.11.3<br>
  Yarn is no longer available. I tried doing a global install again hoping it would add it to my v8.11.3 folder but it keeps trying to add it to v8.11.0</p>
  
  <p>I've even deleted folder v8.11.0 but it just recreates it when I run npm install -g yarn</p>
  
  <p>How can I get it to install so I can use yarn using any node version switch in nvm</p>