title: fill between two lines in polar coordinates
body: <p>I'm trying to fill in the space between two lines that aren't closed at both ends. I can't get plt.fill_between with plt.polar, any ideas? Here's the code I'm using to draw the lines:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np 
  
  inner_offset = 0.05
  r = np.arange(inner_offset,1. + inner_offset,1./720.)
  theta = np.arange(0.,2.,1./360.)*np.pi 
  
  plt.polar(theta/2.,r) #first part of spiral
  plt.polar((theta/2.)+(np.pi/3.),r)
  
  plt.show()
  </code></pre>