title: error while installing go from source
body: <p>i am trying to install go from source </p>
  
  <p>i follow this steps </p>
  
  <pre><code>git clone https://go.googlesource.com/go
  cd go
  git checkout go1.6.1
  
  cd src
  ./all.bash
  </code></pre>
  
  <p>now it gives me the error saying </p>
  
  <pre><code>##### Building Go bootstrap tool.
  cmd/dist
  ERROR: Cannot find /root/go1.4/bin/go.
  Set $GOROOT_BOOTSTRAP to a working Go tree &gt;= Go 1.4.
  </code></pre>
  
  <p>any idea how can i fix this do i just need to set env variable or any other installation is needed ?</p>