Clear out cached entries from _zip_directory_cache.
    See http://www.digi.com/wiki/developer/index.php/Error_messages

def clear_zipimport_cache():
    """Clear out cached entries from _zip_directory_cache.
    See http://www.digi.com/wiki/developer/index.php/Error_messages"""
    import sys, zipimport
    syspath_backup = list(sys.path)
    zipimport._zip_directory_cache.clear()

    # load back items onto sys.path
    sys.path = syspath_backup
    # add this too: see https://mail.python.org/pipermail/python-list/2005-May/353229.html
    sys.path_importer_cache.clear()