title: Can't upgrade JupyterLab to latest version
body: <p>I am trying to upgrade JupyterLab to pre-release but when I check the installed version after upgrading I still get the old version (0.33.11).</p>
  
  <p>To install the pre-release I used:</p>
  
  <p><code>pip install -U --pre jupyterlab</code></p>
  
  <p>I have also tried to upgrade to the latest version (0.35.6) using Anaconda:</p>
  
  <p><code>conda install -c conda-forge jupyterlab</code></p>
  
  <p>I also tried with this:</p>
  
  <p><code>conda update jupyterlab</code></p>
  
  <p>But again in all cases after installation I still get version 0.33.11.</p>
  
  <p>When I run conda again I see that conda donwloads version 0.33.11. This is the message I get from it:</p>
  
  <p>The following packages will be downloaded:</p>
  
  <pre><code>package                    |            build
  ---------------------------|-----------------
  conda-4.6.14               |           py27_0         2.1 MB
  jupyterlab-0.33.11         |           py27_0        10.0 MB
  ------------------------------------------------------------
                                         Total:        12.0 MB
  </code></pre>