title: Does git lock a remote for writing when a user pushes?
body: <p>If two or more users simultaneously push their local repo states to the same remote at the same time, does git:</p>
  
  <ol>
  <li><p>lock the remote commit/branch/repo for writing before it finishes off with one user's <em>entire batch of commits</em> before committing another user's?</p></li>
  <li><p>Or does it release the lock on a commit/repo/branch it holds after it writes a <em>single commit from a single user</em> out of his batch of N commits?</p></li>
  </ol>
  
  <p>The first would make sense but I thought I would ask anyway.</p>