Something is fishy with AR 3.0

lib/delayed/backend/active_record.rb

@@ -139,7 +139,7 @@ def self.reserve_with_scope_using_optimized_postgres(ready_scope, worker, now)
  # when attempting to get the next available job
  # https://www.postgresql.org/docs/9.5/sql-select.html#SQL-FOR-UPDATE-SHARE
  if connection.send(:postgresql_version) >= 9_05_00 # rubocop:disable Style/NumericLiterals
- subquery += " SKIP LOCKED"
+ subquery = "#{subquery} SKIP LOCKED"
  end
 
  quoted_name = connection.quote_table_name(table_name)