Redis Bgsave process inherits sockets

Redis close listening socket when fork bgsave process, but didn't close other sockets. And it may cause socket hung up util bgsave exits.

127.0.0.1:9379> bgsave
Background saving started
127.0.0.1:9379> get a
(nil)
(26.79s)

get command wait 26.79s util bgsave process exits.

Thanks~