title: Git ignore locally deleted folder
body: <p>I have a Ruby on Rails application which crashes when <code>vendor/rails</code> is present but works fine if it is not. I need to keep this folder deleted in my local copy so that I can work, but I don't want this deletion to ever be committed. Someone put it there for a reason.</p>
  
  <p>So how do I delete this folder without it coming up in <code>git status</code> as a thousand deleted files? Obviously <code>.gitignore</code> won't work since you can't ignore files which are already tracked. Neither do any of the solutions listed <a href="https://stackoverflow.com/questions/2718372/git-ignore-deleted-files">here</a> (<code>git update-index --assume-unchanged</code>) work.</p>