Pipelining commands on a Redis instance is deprecated and will be removed in Redis 5.0.0.

```
Pipelining commands on a Redis instance is deprecated and will be removed in Redis 5.0.0.

redis.multi do
  redis.get("key")
end

should be replaced by

redis.multi do |pipeline|
  pipeline.get("key")
end

called from rack-cas/session_store/redis.rb:19:in `write'
```