To stop emitting the warnings, just add RUBYOPT=-W:no-deprecated.

However, a ActiveRecord::Rollback within the nested transaction will be caught by the block of the nested transaction, but will be ignored by the outer transaction, and not cause a roll back! To avoid this unexpected behaviour, you have to explicitly tell rails for each transaction to indeed use proper nesting: CopyActiveRecord::Base.transaction(joinable: false, requires_new: true) do # inner code end This is a safer default for working with custom transactions.