title: Seaborn tsplot not showing CI bands
body: <p>I have a sample dataframe <a href="https://www.dropbox.com/s/d9ublo17h8lundl/test.pickle?dl=0" rel="nofollow noreferrer">here</a> (it's the pickle for the <code>df</code>).  When I do the following:</p>
  
  <pre><code>df = pd.read_pickle('test.pickle')
  sns.tsplot(data=df.sort('time', ascending=True), time='time', unit='entity', condition='prior_type', value='perf')
  </code></pre>
  
  <p>I get the following output (nothing):
  <img src="https://i.stack.imgur.com/WpAdL.png" alt="enter image description here"></p>
  
  <p>When I change it to use <code>unit_traces</code> I can actually see the data</p>
  
  <pre><code>sns.tsplot(data=df.sort('time', ascending=True), time='time', unit='entity', condition='prior_type', value='perf', err_style='unit_traces')
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/lnrC9.png" alt="enter image description here"></p>
  
  <p>My question is why can't I see the CI's?  The data is a bit disjoint in some places but I would still think it should be able to come up with some sort of confidence band.  Am I missing something here?</p>