title: KDE fails with two points?
body: <p>The following trivial example returns a singular matrix. Why? Any ways to overcome it?</p>
  
  <pre><code>In: from scipy.stats import gaussian_kde
  Out:
  
  In:  points
  Out: (array([63, 84]), array([46, 42]))
  
  In:  gaussian_kde(points)
  Out: (array([63, 84]), array([46, 42]))
  
  LinAlgError: singular matrix
  </code></pre>