title: find out which git commit a file was taken from
body: <p>A collaborator that does not use version control has sent me a file with some local modifications. Now he went on vacation. I would like to find out which version his edits were based on. </p>
  
  <p>I suppose the most promising approach is to somehow iterate over the most recent commits and check for which the length of the diff is minimal.</p>
  
  <p>Is there some ready-made functionality for this, or would I need to code this myself? Not being a git expert myself, what would be the most promising way to proceed? </p>