Fix bug in pipeline with Redis

Issues was: select from db return tuple, not single item

exa/exa/pipelines.py

@@ -17,8 +17,7 @@ class ExaPipeline(object):
         self.db = Database(**db)
         self.buffer = redis.StrictRedis()
         for i in self.db.select('select url from wp_esi_news_accept'):
-            self.buffer.set(i, True)
-        self.urls = {i[0] for i in self.db.select('select url from wp_esi_news_accept')}
+            self.buffer.set(i[0], True)
         super(ExaPipeline, self).__init__()
 
     def open_spider(self, spider):