title: Brew update errors
body: <p>I'm trying to install Ruby/RVM/Rails on my Mac but I was unaware that I had to install Homebrew first.  Upon running the recommended <code>ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)"</code> to install, all that happened is <code>env</code> and <code>bash</code> ran alternating.</p>
  
  <p>I followed <a href="https://github.com/mxcl/homebrew/wiki/Installation#untar-anywhere" rel="nofollow">https://github.com/mxcl/homebrew/wiki/Installation#untar-anywhere</a>  &lt;- these instructions on installing.  Downloaded and untar'd my files in /usr/local/ and symlinked them to /usr/bin/ and /usr/local/bin.</p>
  
  <p>I then tried running <code>rvm get head</code> which succeeded, and <code>rvm requirements</code> which replied with</p>
  
  <pre><code>Installing requirements for osx/10.8/x86_64, might require sudo password
  Skipping `brew update` make sure your formulas are up to date.
  Cowardly refusing to continue at this prefix: /usr
  Cowardly refusing to continue at this prefix: /usr
  </code></pre>
  
  <p>I tried running <code>brew update</code> and <code>Cowardly refusing to continue at this prefix: /usr</code> appears again.  I ran all these with <code>sudo</code> and same results.</p>
  
  <p>Any help  would be much appreciated!  I would be willing to uninstall everything and start from scratch if someone could give me steps on doing that.</p>