title: Can Git ignore files that has the same content but updated timestamp
body: <p>I'm using FTP in my recent web project. And I try use git to keep a local backup of all the changes on the FTP. It seems that the FTP server failed to support MFMT command (or some other thing I got wrong), the downloaded files do not preserve their timestamps.</p>
  
  <p>When I do a git diff with the newly downloaded files, Git marks every files as changed.</p>
  
  <p>Is there anyway I can tell Git to commit based on the diff result instead of the timestamp?</p>