title: ValueError when using matplotlib tight_layout()
body: <p>Ok, this is my first time asking a question on here, so please be patient with me ;-)</p>
  
  <p>I'm trying to create a series of subplots (with two y-axes each) in a figure using matplotlib and then saving that figure. I'm using GridSpec to create a grid for the subplots and realised that they're overlapping a little, which I don't want. So I'm trying to use tight_layout() to sort this out, which according to the matplotlib documentation should work just fine. Simplifying things a bit, my code looks something like this:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import matplotlib.gridspec as gridspec
  
  fig = plt.figure(num=None, facecolor='w', edgecolor='k')
  grid = gridspec.GridSpec(2, numRows) 
  # numRows comes from the number of subplots required
  
  # then I loop over all the data files I'm importing and create a subplot with two y-axes each time
    ax1 = fig.add_subplot(grid[column, row])
    # now I do all sorts of stuff with ax1...
    ax2 = ax1.twinx()
    # again doing some stuff here
  </code></pre>
  
  <p>After the loop for data processing is done and I have created all the subplots, I eventually end with </p>
  
  <pre><code>fig.tight_layout()
  fig.savefig(str(location))
  </code></pre>
  
  <p>As far as I can work out, this should work, however when calling tight_layout(), I get a ValueError from the function self.subplotpars: left cannot be >= right. My question is: How do I figure out what's causing this error and how do I fix it?</p>