add some buffer to our cache

scrape.py

@@ -172,7 +172,9 @@ async def main():
 
                     # add url to cache
                     cache += [post['url']]
-                    while len(cache) > len(blog):
+                    # check for double the post count, to have some buffer for manually purging URLs
+                    # otherwise the cache could reshuffle when you remove too many URLs at once
+                    while len(cache) > len(blog)*2:
                         cache.remove(cache[0])
                     set_state = await matrix[next(iter(matrix))].room_put_state(room_id=admin_room,
                                                                                 event_type=event_type_prefix+'cache',