title: Impossible to checkout a git commit
body: <p>I'm trying to checkout a specific commit that I see on GitHub:</p>
  
  <p><a href="https://github.com/mapbox/node-sqlite3/commit/b8907e79fc3fb52803b5a05c106948911dcd77ac" rel="nofollow noreferrer">https://github.com/mapbox/node-sqlite3/commit/b8907e79fc3fb52803b5a05c106948911dcd77ac</a></p>
  
  <p>However, a local checkout fails:</p>
  
  <pre><code>$ git checkout b8907e79fc3fb52803b5a05c106948911dcd77ac
  fatal: reference is not a tree: b8907e79fc3fb52803b5a05c106948911dcd77ac
  </code></pre>
  
  <p>A <code>git reset</code> failed with the same error.</p>
  
  <p>Any ideas?</p>