title: Refering the %USERPROFILE% environment variable failed
body: <p>I create a new environment variable in the environment variable settings GUI tool in Windows
  Name: ATOM_HOME
  Value: %USERPROFILE%\Downloads\atom-windows\Atom</p>
  
  <p>When I echo %USERPROFILE% in a new cmd window
  <code>echo %ATOM_HOME%</code>
  it return <code>%USERPROFILE%\Downloads\atom-windows\Atom</code> which doesn't expand the %USERPROFILE% variale.</p>
  
  <p>If I echo %TMP% which is predefined as  <code>TMP=%USERPROFILE%\AppData\Local\Temp</code> , I get 
  <code>C:\Users\myname\AppData\Local\Temp</code> which does expand the %USERPROFILE% variale.</p>
  
  <p>How do I reference %USERPROFILE% in a new environment variable?</p>