memoize_articles not working?

[Rapid1898-code]

Hello - i try to test the build function using this example -

import newspaper
cnn_paper = newspaper.build('http://cnn.com', memoize_articles=False)
for article in cnn_paper.articles:
    print(article.url)
print(cnn_paper.size())

When i run this the first time it works fine and all the article-links are outputted.
But when i run it the second time - using the memoize_articles parameter as you can see above - its only outputting 0 and with an error

(test) C:\DEVNEU\Python-Diverses\newspaper4k>python try2.py
C:\DEVNEU\.venv\test\Lib\site-packages\newspaper\source.py:260: FutureWarning: The behavior of this method will change in future versions. Use specific 'len(elem)' or 'elem is not None' test instead.
  if feed.doc:
0

Why is that? Shouldn´t the parameter be used to get nevertheless all articles?
Or how can i get to this article-links when i have allready fetched them before?