It uses the python twitterAPI installed from.

from twitter import *
datetime, twt, rts, [], [], []
max_id = 123456789
count = 200
timeline = t.statuses.user_timeline ((user_id = user_id, count = count, max_id = max_id, exclude_replies = True, include_rts = True))
for tweet in timeline:
   twt.append (tweet ['text'])
   datetime.append (tweet ['created_at'])
   rts.append (tweet ['retweeted'])

Tweet retweet flags are all false. In other words, everything in rts is False.
(Text, tweet date, etc. can be acquired normally)
Does anyone know the cause?

This article was written in 2010, but this bug seems to have occurred at that time.
Reference url (https://groups.google.com/forum/#!topic/twitter-development-talk/Iu4P0uaJK9c)