title: git diff sees whole file as changed when it's not
body: <p>The git diff engine is seeing a whole file as changed when it has not. For example, take this commit: <a href="https://github.com/etiago/phpvirtualbox/commit/626e09958384f479f94011ac3b8301bd497aec51" rel="noreferrer">https://github.com/etiago/phpvirtualbox/commit/626e09958384f479f94011ac3b8301bd497aec51</a></p>
  
  <p>Here we see that the file <strong>lib/vboxconnector.php</strong> has 2807 additions and 2778 deletions. Additionally, from doing a manual git diff I find that indeed, the whole file is taken in as a deletion (marked with minus) and a whole new file is taken as an addition. However, the files have a lot in common which Git simply ignored.</p>
  
  <p>I've looked at <a href="https://stackoverflow.com/questions/12876350/diff-returning-entire-file-for-identical-files">diff returning entire file for identical files</a> but it does not seem to be the case as no white space changes exist between the two commits.</p>
  
  <p>Furthermore, taking the two commits of the file (the one in <code>626e09958384f479f94011ac3b8301bd497aec51</code> and <code>626e09958384f479f94011ac3b8301bd497aec51^1</code>) and diff'ing them using Meld, I get the right diff analysis.</p>
  
  <p>I've uploaded the two commits of the file to my Dropbox for convenience: <a href="https://dl.dropboxusercontent.com/u/59728/disposables/vboxconnector.php_1" rel="noreferrer">commit_1</a> <a href="https://dl.dropboxusercontent.com/u/59728/disposables/vboxconnector.php_2" rel="noreferrer">commit_2</a>.</p>