title: I want change directory and run command in fabric
body: <p>I want to change directory and when I run command with cd('myApp') I get: </p>
  
  <pre><code>No hosts found. Please specify (single) host string for connection:
  </code></pre>
  
  <p>I have this code:</p>
  
  <pre><code>def example():
      local('sudo apt-get install python-dev libmysqlclient-dev')
      local('pip install MySQL-python')
      local('sudo apt-get install apache2')
      with cd('myApp'):
          run('pwd')
          run('python manage.py syncdb --no-initial-data')
          run('python manage.py migrate')
      print(green('DONE.'))
  </code></pre>