title: repo about .git/HEAD: error: manifest missing or unreadable -- please run init
body: <p>I was downloading android 4.4 source code using repo(in ubuntu). Last time I killed repo process by pressing the key combination: Ctrl+Z, and when I started it this time by using the command: "repo init" and "repo sync", I got the following errors:</p>
  
  <blockquote>
    <p>error: in <code>sync</code>: [Errno 2] No such file or directory:
    u'/home/ubuntu/workspace/packages/apps/VoiceDialer/.git/HEAD' error:
    manifest missing or unreadable -- please run init</p>
  </blockquote>
  
  <p>I've tried "run init", which displays no errors. But the problem remains after running "repo init". What should I do? Is there any way to tell repo to reproduce the ./git/HEAD file?</p>