Don't try to connect to redis from client-side sidekiq.

lib/sidetiq/schedulable.rb

@@ -42,6 +42,7 @@ module Sidetiq
         schedule.set_options(options)
 
         # deleting schedulable keys if schedule changed since last reccurence definition
+        if Sidekiq.server?
           old_description = get_schedulable_key("schedule_description")
           if old_description != schedule.to_s
             get_schedulable_keys.map do |key|
@@ -50,6 +51,7 @@ module Sidetiq
             set_schedulable_key("schedule_description", schedule.to_s)
           end
         end
+      end
 
       private