title: Git clone failed with "refs/heads/master does not point to a valid object"
body: <pre><code>C:\Users\xxx\temp&gt;git clone D:\userdata\Dropbox\gitrepo\main.git
  Cloning into 'main'...
  error: unable to find 0fb6364a712239ae87e4abb35e155a04e960c788
  error: refs/heads/master does not point to a valid object!
  done.
  error: Trying to write ref HEAD with nonexistent object 0fb6364a712239ae87e4abb3
  5e155a04e960c788
  fatal: Cannot update the ref 'HEAD'.
  fatal: The remote end hung up unexpectedly
  </code></pre>
  
  <p>My git repo is stored in dropbox, on my own computer this command works fine, but on another computer it gives me the above error. Any ideas? (of course the repo is synchronized)</p>
  
  <p>Thanks.</p>