fix test that breaks if other clients are connected to the redis server
fix test that breaks if other clients are connected to the redis server

mozillazg/redis-py-doc,alisaifee/redis-py,5977862/redis-py,andymccurdy/redis-py,redis/redis-py,5977862/redis-py,redis/redis-py,andymccurdy/redis-py,mozillazg/redis-py-doc,5977862/redis-py,alisaifee/redis-py,andymccurdy/redis-py