|Subject:||Test::NoWarnings should be test_required, not just author-tests|
Test::NoWarnings is used in many t/* tests that have no guards to prevent running except in author mode.
Its thus appropriate Test::NoWarnings be displayed in build/test requires. ( Though I understand MI only natively handles test as build still :(, but being declared there is better than not at all )
Test::NoWarnings is otherwise nowhere to be found in the dependency graph of Mail::Builder, so its failure not having occurred in the wild is mostly luck =).