Small performance improvement.

modules/scheduling/calender_fetcher.py

@@ -278,15 +278,15 @@ class CalendarFetcher:
         servicetype = "api_tank_playlist"
         playlist = None
 
+        if not playlist_id:
+            return None
+
         # If playlist is already fetched, use the existing one
         for playlist in fetched_playlists:
             if playlist["id"] == playlist_id:
                 self.logger.debug("Playlist #%s already fetched" % playlist_id)
                 return playlist
 
-        if not playlist_id:
-            return None
-
         url = self.__build_url__(servicetype, "${ID}", playlist_id)
         json_response = self.__fetch_data__(servicetype, url)