fix broken tests on renaming feature

Author: jsvd

lib/logstash/inputs/redis.rb

@@ -156,9 +156,11 @@ def connect
  redis = new_redis_instance
 
  # register any renamed Redis commands
- client_command_map = redis.client.command_map
- @command_map.each do |name, renamed|
- client_command_map[name.to_sym] = renamed.to_sym
+ if @command_map.any?
+ client_command_map = redis.client.command_map
+ @command_map.each do |name, renamed|
+ client_command_map[name.to_sym] = renamed.to_sym
+ end
  end
 
  load_batch_script(redis) if batched? && is_list_type?