class Redis::MultiConnection

def multi
  raise Redis::BaseError, "Can't nest multi transaction"
end

https://redis.io/commands/blpop/#blpop-inside-a-multi--exec-transaction
It shouldn't be done though.
Blocking commands inside transaction behave like non-blocking.

def send_blocking_command(command, _timeout, &block)
  send_command(command, &block)
end