title: VTS suite doesn't run because of exception
body: <p>I tried to run the vts suite with:</p>
  
  <pre><code>run vts
  </code></pre>
  
  <p>But it doesn't run any module and gives this exception:</p>
  
  <pre><code> I/ResultReporter: Invocation finished in 4s. PASSED: 0, FAILED: 0, MODULES: 0 of 150
  </code></pre>
  
  <p>and gives the following exception</p>
  
  <pre><code>E/CommandScheduler: com.android.tradefed.targetprep.TargetSetupError: Failed to create virtualenv
  java.lang.RuntimeException: com.android.tradefed.targetprep.TargetSetupError: Failed to create virtualenv
  </code></pre>