title: Git: exclude committed file from pull request
body: <p>I have a repo to which I have pushed my stuff. I have realized that I am pushing the <code>.idea/workspace.xml</code>, which I should have ignored (lot of useless configuration stuff).</p>
  
  <p>Now it is on my remote repo, and I need to do a pull request.
  Can the offending file be excluded from the pull request?</p>