title: scipy.fftpack's FFT freezing
body: <p>When computing a FFT of an array of size ~ 1.5 million items:</p>
  
  <pre><code>import numpy as np
  from scipy.fftpack import fft
  
  x0 = np.ones(1492828, dtype=np.int32)
  fft(x0)
  print 'hello'
  </code></pre>
  
  <p>the FFT computation never finishes, and the program is freezing. If I change <code>1492828</code> to <code>1492827</code>, it seems to work. But if I change <code>1492828</code> to <code>1492826</code>, it still freezes, which is kind of strange.</p>
  
  <p>Is this a known bug?</p>
  
  <p>Note: </p>
  
  <ul>
  <li><p>The CPU stays at 25% (normal, I have a 4-core CPU), and the RAM usage of the Python process stays at ~75 MB</p></li>
  <li><p>I'm using Python 2.7.15 64-bit on Windows 7 64-bit: </p>
  
  <pre><code>print scipy.__version__     # 1.1.0
  print sys.version           # 2.7.15 (v2.7.15:ca079a3ea3, Apr 30 2018, 16:30:26) [MSC v.1500 64 bit (AMD64)]
  </code></pre></li>
  </ul>