take care of FutureWarning

/Library/Python/2.7/site-packages/junos_eznc-1.1.0.dev-py2.7.egg/jnpr/junos/utils/config.py:289: FutureWarning: The behavior of this method will change in future versions. Use specific 'len(elem)' or 'elem is not None' test instead.
  if any([e.find('[error-severity="error"]') for e in rerrs]):