title: AppEngine log not accepting context
body: <p>According to the <a href="https://cloud.google.com/appengine/docs/standard/go/logs/" rel="nofollow noreferrer">documentation</a> I can use <code>log.Errorf(ctx, "whatever: %v", err)</code></p>
  
  <p>Somehow that isn't working for me. I have <code>ctx</code> declared as an <code>appengine.Context</code>, as in the documentation example, but Go is complaining that I need to pass a <code>net/context</code> instead!? I would assume that AppEngine would <strong>ONLY</strong> accept an AppEngine context, and nothing else.</p>