fix old_cache check

scrape.py

@@ -2,6 +2,7 @@ from os import environ
 
 import asyncio
 import re
+from copy import deepcopy
 from datetime import datetime, timedelta
 from random import randrange
 
@@ -146,7 +147,7 @@ async def main():
                     cache[category] = []
                 if hasattr(cache_state, 'content') and 'url_list' in cache_state.content:
                     cache[category] += cache_state.content['url_list']
-            old_cache = cache
+            old_cache = deepcopy(cache)
 
             # scrape all blog posts and process them
             blog = get_blog()