Ignore Shutdown exception in retry middleware, fixes #897

Changes.md

@@ -1,6 +1,7 @@
 2.11.3
 -----------
 
+- Fix unclean shutdown leading to duplicate jobs [#897]
 - Add Korean locale [#890]
 
 2.11.2

lib/sidekiq/middleware/server/retry_jobs.rb

@@ -48,6 +48,9 @@ module Sidekiq
 
         def call(worker, msg, queue)
           yield
+        rescue Sidekiq::Shutdown
+          # ignore, will be pushed back onto queue
+          raise
         rescue Exception => e
           raise e unless msg['retry']
           max_retry_attempts = retry_attempts_from(msg['retry'], DEFAULT_MAX_RETRY_ATTEMPTS)