title: How do you fork a repo whose upstream you've already forked?
body: <p>I want to fork namecoin/namecoin, but I've already forked bitcoin/bitcoin.  The latter is the upstream parent of the former.  The forkchain is:</p>
  
  <p>bitcoin/bitcoin -> vinced/namecoin -> namecoin/namecoin</p>
  
  <p>When I fork namecoin/namecoin, Github just redirects me to my myuserid/bitcoin fork, instead of creating a new myuserid/namecoin fork.  It appears to Github that they are the same project, but they are not.  </p>
  
  <p>Anyone know how to do this?</p>