I really don't like unless blocks, I use unless exclusively for postfixed conditions, because with a block, the temptation of introducing an "else" later on is dangerous... What about unless (condition) { } else { } ?

I would really prefer to see if (! $self->destroyed_session) here (same remark for the private method).

I know these can be subjective remarks, but if we can share common coding guidelines in the core, it's better ;)

BTW @celogeek : do we have a PerlCritic policy implemented with dzil? This kind of stuff should be triggered by our policy.