First, here's the contents of our config file:
<FOO>
        FooThing = 1
        FooThang = 7
</FOO>

BAR = semisomething string

FooThang: 7
BAR: semisomething string
All well and good.

Now we haven't reconsecrated $self, so: BAR: semisomething string
And this looks right:
        Is $self a Config::General? ($self->isa(Config::General) returns): true
        Is $self a Config::General::Extended? ($self->isa(Config::General::Extended) returns): true

Lo! the blessing ensues...
Uh-oh: BAR: Can't locate object method "BAR" via package "MyConfig" at (eval 14) line 1.

Moreover:
        Is $self a Config::General? ($self->isa(Config::General) returns): true
        Is $self a Config::General::Extended? ($self->isa(Config::General::Extended) returns): false