title: Git error when pushing - update_ref failed
body: <p>I have a problem when i try to push my local commits, it has probably happened when Android Studio has crushed. Here is the error:</p>
  
  <blockquote>
    <p>update_ref failed for ref 'refs/remotes/origin/master': cannot lock
    ref 'refs/remotes/origin/master': unable to resolve reference
    refs/remotes/origin/master: Invalid argument</p>
  </blockquote>
  
  <p><code>$git stash</code> says that <code>HEAD</code> is now at my latest commit.</p>
  
  <p>I'm still a beginner in git and I have no idea how to fix it.. What can I do?</p>