title: Can't use /= on numpy array
body: <p>On a <code>numpy</code> array, why is it I can successfully use <code>/ 2</code>:</p>
  
  <pre><code>&gt;&gt;&gt; a=np.array([2, 4, 6])
  &gt;&gt;&gt; a = a / 2
  &gt;&gt;&gt; a
  array([ 1.,  2.,  3.])
  </code></pre>
  
  <p>But I cannot use <code>a /= 2</code>?</p>
  
  <pre><code>&gt;&gt;&gt; a=np.array([2, 4, 6])
  &gt;&gt;&gt; a /= 2
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  TypeError: No loop matching the specified signature and casting
  was found for ufunc true_divide
  </code></pre>
  
  <p>I've seen <a href="https://github.com/numpy/numpy/issues/6464" rel="noreferrer">numpy Issue 6464</a>, but don't understand from reading it and the linked release notes the reason this doesn't work.</p>
  
  <p>Is there any way to get <code>/=</code> to work as expected?</p>