gem update --system returns "no implicit conversion of nil into String"
<p>Running gem update --system keeps returning error</p>

<pre><code># gem update --system
    Updating rubygems-update
    ERROR:  While executing gem ... (TypeError)
    no implicit conversion of nil into String
</code></pre>

<p>How to fix it? <br>
Verbose: <a href="http://pastebin.com/2uBYEMTi" rel="noreferrer">http://pastebin.com/2uBYEMTi</a></p>