Merge pull request #283 from tjkuson/user-warning-fix

Change deprecation check

Author: aerkalov

ebooklib/epub.py

@@ -1395,7 +1395,7 @@ def __init__(self, epub_file_name, options=None):
  self._check_deprecated()
 
  def _check_deprecated(self):
- if not self.options.get('ignore_ncx'):
+ if self.options.get('ignore_ncx') is None:
  warnings.warn('In the future version we will turn default option ignore_ncx to True.')
 
  def process(self):