title: Git rm --cached and checkout
body: <p>I've issued the following command</p>
  
  <pre><code>git rm --cached .idea
  </code></pre>
  
  <p>on my <code>develop</code> branch, 'cause i don't want to track ide config files. Files have been removed from index but they're still on filesystem, which is exactly my original goal.</p>
  
  <p>Now when i try to checkout another branch, git fails because they're still in the index of the other branch - this is expected.</p>
  
  <p>However, i need to remove these files from the index of any branch, so how can i issue the same <code>git rm --cached</code> command on a branch i can't checkout to?</p>