title: How can I debug git/git-shell related problems?
body: <p>How can I have some debug information regarding git/git-shell? </p>
  
  <p>I had a problem, that <code>user1</code> could clone a repository without problem, while <code>user2</code> could clone only an empty one. I had set <code>GIT_TRACE=1</code>, but nothing useful was told.</p>
  
  <p>Finally, after a long trial and error, it turned out that it was a permission problem on a file. An appropriate error message could short-circuit this problem.</p>