title: numpy : indexes too big giving sometimes exceptions, sometimes not
body: <p>It seems really stupid, but I'm wondering why the following code (numpy 1.11.2) raise an exception:</p>
  
  <pre><code>import numpy as npy
  a = npy.arange(0,10)
  a[10]
  </code></pre>
  
  <p>An not this one:</p>
  
  <pre><code>import numpy as npy
  a = npy.arange(0,10)
  a[1:100]
  </code></pre>
  
  <p>I can understand, when we want to take part of an array, that's possible we don't really care if the index becomes too big (just taking what is in the array), but it seems a bit tricky too me: it's quite easy too didn't notice you're actually having a but on the way you're counting indexes, without an exception raising.</p>