Fix html_for_tweet for pre-quote implementation tweet html

Author: ping

twython/api.py

@@ -597,7 +597,7 @@ def html_for_tweet(tweet, use_display_url=True, use_expanded_url=False, expand_q
                     text = text.replace(tweet['text'][start:end],
                                         url_html % (entity['url'], shown_url))
 
-        if expand_quoted_status and tweet['is_quote_status']:
+        if expand_quoted_status and tweet.get('is_quote_status'):
             quoted_status = tweet['quoted_status']
             text += '<blockquote class="twython-quote">%(quote)s<cite><a href="%(quote_tweet_link)s">' \
                     '<span class="twython-quote-user-name">%(quote_user_name)s</span>' \