title: Create a git patch between repository and non-repository
body: <p>I have a situation where a folder needs to be patched to be the same state as a repository.  Consider this short tale:</p>
  
  <p>Ten years age Goofus and Gallant are somewhat alike and at a fork in the road Gallant moves onward and becomes a better person.  Goofus hangs out and does nothing.  The almighty pointy hair decrees Goofus must become more like Gallant again.  How can Gallant patch Goofus without making him a clone ?</p>
  
  <ol>
  <li>Goofus and Gallant similar but not identical</li>
  <li>Gallant enters the repository</li>
  <li>Gallant milestone reached</li>
  <li>Goofus needs to be patched to Gallant</li>
  </ol>
  
  <p>What's the best way to get the patch ?</p>
  
  <p>Should I make a branch and mutate Gallant back to Goofus and then make an inverse patch ?</p>