title: math.sqrt domain error when square rooting a positive number
body: <p>I am getting a domain error when square rooting a positive number. It originally was occurring in a complicated program but I was able to reproduce the bug as simply as doing the following:</p>
  
  <pre><code>Microsoft Windows [Version 10.0.16251.1002]
  (c) 2017 Microsoft Corporation. All rights reserved.
  
  C:\Users\Adam&gt;python
  Python 3.6.2 (v3.6.2:5fd33b5, Jul  8 2017, 04:14:34) [MSC v.1900 32 bit (Intel)] on win32
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import math
  &gt;&gt;&gt; math.sqrt(1.3)
  Traceback (most recent call last):
   File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  ValueError: math domain error
  &gt;&gt;&gt;
  </code></pre>
  
  <p>I upgraded from version 3.6.1 to 3.6.2 to try to resolve the issue and restarted my computer but it is still occurring. Some numbers are working (1.2, 1.4) and some others are also not working (1.128).</p>
  
  <p>The code I'm working on is working in Ubuntu but not in Win10 and this seems to be the issue stopping it from working. </p>