title: Pull Request, ignore some file changes
body: <p>When I do a Pull Request on GitHub (against master branch), can we ignore some file changes, like</p>
  
  <ul>
  <li>we have one file named 'fileA' in branch 'release', and we have the same file in 'master', but we do some changes in 'fileA' in branch 'release'</li>
  <li>when we do a Pull Request, is there any way we can ignore the changes in 'fileA', do not let that merge into 'master'.</li>
  </ul>