title: How to see the commit after which a repository was forked using git?
body: <p>I have an original repo A, suppose after commit10 I forked repo B. repo A continued developing and so did repo B. I want to see only things which were added by repoB person i.e. diff of HEAD and commit10. </p>
  
  <p>How to figure out what is commit10, at what point was repoB forked?</p>
  
  <p>There are many similar questions on stackoverflow but they are trying to diff current version of two repos. That is different from what I need.</p>